RESEARCH ON METHOD FOR GEODETIC MONITORING, ANALYZING FOUNDATION AND BASEMENT DEFORMATION OF HIGH RISE BUILDINGS IN THE CONSTRUCTION PERIOD

MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF MINING AND GEOLOGY TRAN NGOC DONG RESEARCH ON METHOD FOR GEODETIC MONITORING, ANALYZING FOUNDATION AND BASEMENT DEFORMATION OF HIGH-RISE BUILDINGS IN THE CONSTRUCTION PERIOD Study field: Geodesy and mapping Code: 62520503 SUMMARY OF ENGINEERING DOCTORAL DISSERTATION Hanoi - 2014 The dissertation has been completed at the Department of Engineering surveying, of Surveying Faculty, Hanoi University of Mining and Geology Scientific Supervisors: Assoc. Prof. Dr. Tran Khanh Hanoi university of Mining and Geology Examiner 1: Dr. Duong Chi Cong VietNam Institute of Geodesy and cartography Examiner 2: Dr. Nguyen Van Van Association of Geodesy, Maps and Remote Sensing of Vietnam Examiner 3: Dr. Vu Van Dong Defense Mapping Agency of VietNam - General Staff The dissertation will be defended at the University examination Council at the Hanoi University of Mining and Geology, at… h, ……………… 2014 This dissertation can be referenced at the National library or at the library of the Hanoi University of Mining and Geology. 1 INTRODUCTION 1. The importance of dissertation Recently, when excavating holes for constructing the foundation and basement of a high-rise building, many adjacent works have confronted heavy breakdowns, which caused many economic losses and concern in society. Those weaknesses are mainly caused by monitoring and analyzing impacts that are not conducted in time of the process of constructing the foundation and basement. The issue on monitoring, analyzing the deformation of foundation and basement of a high-rise building in the construction period becomes urgent. However, until now, this issue has not been paid crucial attention to. There has not had any careful, comprehensive research and proposed technical solution. Thus, researching the method of monitoring, analyzing foundation and basement deformation of a high-rise building in the construction period is very necessary. This contributes to ensuring safety for not only the entire building but also adjacent buildings, people and normal activities of the residents. 2. Purpose, object and scope of research - The dissertation aims at contributing to developing and finalizing the method of monitoring, analyzing deformation, evaluating and modeling the displacement process of the foundation and basement of the high-rise building in the construction period. - Object of research is: the method of monitoring, analyzing deformation of foundation and basement of high-rise buildings in Vietnam. - Scope of research of the dissertation consists of: Researching the method of surveying, using sensing to monitor the deformation of foundation and basement of the high-rise buildings; Researching the combination of method of surveying and using sensing to increase the quality and effectiveness of monitoring the deformation of the foundation and basement; Analyzing, evaluating and modeling the displacement process of the foundation and diaphragm wall of the high-rise buildings in the period of constructing the foundation and basement. 3. Contents of research 1- Researching the combination of method of surveying and using sensingto monitor the settlement of the foundation and displacement of the diaphragm wall of the high- rise buildings in the period of constructing the foundation and basement. 2- Researching the application of the automatic monitoring system for monitoring the displacement of the diaphragm wall continuously. 3- Building the displacement model; Analyzing, evaluating and predicting the displacement of the foundation and diaphragm wall of the high-rise buildings. 4- Developing the software for analyzing the deformation of the foundation and basement of the high-rise buildings. 4. Method of research Method of research consists of statistics, analysis, experiment, comparison, informatics application and mathematical method. 5. Scientific and practical meaning of the Dissertation Scientific meaning: The Dissertation contributes to developing and finalizing the method of monitoring, analyzing deformation and modeling the displacement process 2 of the foundation and basement of high-rise buildings in the construction period. Practical meaning: The research results of the Dissertation could be applied for monitoring, analyzing, evaluating and predicting the foundation and basement of high-rise buildings in the construction period and adjacent buildings. 6. Theoretical points to be defended - First theoretical point: The solution in combining the surveying method and method of using sensing as proposed in the Dissertation allows increasing the effectiveness of monitoring the deformation of foundation and diaphragm wall of high-rise buildings. - Second theoretical point: The work deformation model that is developed based on the monitored data allows evaluating settlement as well as displacement of the foundation and diaphragm wall of high-rise buildings chronologically, in space and evaluating the dependence between deformation and its agent. 7. New points of the Dissertation 1- The Dissertation suggests the solution in combining the surveying method and method of using sensing as proposed in the Dissertation allows increasing the effectiveness of monitoring the deformation of foundation and diaphragm wall of high-rise buildings. 2- The Dissertation suggests developing the models on displacement of the foundation and diaphragm wall of high-rise buildings chronologically, in space and evaluating the dependence between deformation and its agents. 3- The Dissertation suggests developing the software for analyzing foundation and basement deformation of high-rise buildings. 8. Structure and contents of the Dissertation Apart from Preface, Conclusion, the Dissertation is represented in five Chapters with more than 130 pages of interpretations, figures and charts. Chapter 1. OVERVIEW ABOUT MONITORING THE DEFORMATION OF THE FOUNDATION AND BASEMENT OF HIGH-RISE BUILDINGS IN THE CONSTRUCTION PERIOD 1.1. Overview of foreign research works 1 - Monitoring the displacement of the foundation of high-rise buildings in the construction period of foundation and basement. - Determining monitoring scope [82]. - Monitoring method: Surveying and using sensing [46], [47], [48], [49], [52], [53], [54]. 2 - Analyzing and evaluating the results on monitoring the displacement of the foundation and basement of the high-rise buildings [47], [50], [53], [60], [62]. 3 – Automation of monitoring and processing data [51], [55], [57], [58], [61], [63]. 1.2. Overview of domestic research works 1- Theoretical researches - Researching the method and procedure of monitoring the work deformation [3], [4], [5], [9], [13], [27], [28], [29]. - Researching network design and processing the work deformation monitoring data [2], [10], [15], [19], [[20], [32]. - Researching application of modern devices into monitoring the work deformation [3], [5], [32]. 3 - Researching and analyzing the work deformation [18], [19], [29], [32]. - Researching the application of informatics into processing the work deformation monitoring data [8], [21], [29]. 2 - Deployment of monitoring the building foundation in reality There have been research works [1] in monitoring the foundation of the high-rise buildings. Some of these works have become the National Standards such as [34], [35], [37], [38]. - Determining monitoring scope [36]. - Monitoring method: Surveying and using sensing. 1.3. General evaluation of the research situation 1 - In general, the researches on this field in the world have some points that have not been suitable to the conditions in Vietnam (weak soil, mixed buildings, construction elements, etc.). 2 - In Vietnam, the used modern devices and technologies are mainly imported. Vietnam has not manufactured the specialized measurement devices for monitoring the work deformation. 1.4. Weaknesses and research orientations in the Dissertation At present, the method of surveying and using sensing for monitoring the deformation of the foundation and basement of the high-rise buildings are still separate from each other. Thus, research on combination of the surveying and sensor- used method to increase the quality and effectiveness of monitoring the deformation of the foundation of the high-rise buildings is necessary. Researching the application of the automatic monitoring system into monitoring the displacement of the diaphragm wall of the high-rise buildings continuously to contribute to preventing the accidents that could occur in executing holes is necessary. At present, the monitoring process in this period are just for data collection only without specific analyses and evaluations of the effects of the hole excavating process on the adjacent works. Therefore, it is necessary to research, analyze the monitoring data and developing the model on displacement of the foundation and diaphragm wall to control the accidents that could occur to the work and adjacent works. Chapter 2. MONITORING THE SETTLEMENT OF THE FOUNDATION AND BASEMENT OF THE HIGH-RISE BUILDINGS IN THE CONTRUCTION PERIOD 2.1. Technical requirements on monitoring the settlement in the process of building the foundation and basement of the high-rise buildings 2.1.1. Causes of settlement in the process of executing the foundation and basement In the process of excavating holes for constructing the foundation and basement, when some soil volume is taken, the stress status will be changed. This leads to deformation of the soil block surrounding the excavated holes. Soil will displace to the excavated holes. The displacement extent depends on the quality of the support structure, soil type, distance as well as location and load of the adjacent work. The combination of these displacements will make the ground surface adjacent to the excavated holes settle. If this affected area has works, these works will be deformed. 4 2.1.2. Settlement monitoring contents in the foundation and basement construction process - To monitor settlement of the ground surface; to monitor settlement in line with depth of soil layers surrounding the excavated holes. - To monitor settlement of adjacent works. - To monitor settlement of emerging of the foundation pit (ignite of the excavated hole bottom). - According to [35], measuring and determining the work settlement should be performed immediately after the foundation is built completely. When constructing the basement, the work has had load. Thus, it is necessary to monitor the settlement of the work immediately in this period. 2.1.3. Determination of the settlement monitoring area in the foundation and basement construction process If the design does not indicate the area that should be monitored settlement, we could calculate this affecting area using estimating formulas of the soil mechanics theory. Accordingly, the affecting scope of the soil surrounding the excavated hole is estimated by formula [80]: o o B = H . tg(45 - / 2 ) (2.1) In which: B o - Settlement effect scale of the soil block (m); H - Depth of the diaphragm wall structure (m); φ - Angle of internal friction of soil ( o ). 2.1.4. Requirements on accuracy and settlement monitoring cycle in the foundation and settlement construction process 2.1.4.1. Requirements on accuracy in settlement monitoring Method 1: To base on the predicted settlement value (provided by the designing unit) to determine the requirement on monitoring accuracy. Method 2. It is possible to use the settlement measurement grades in Vietnamese Standard 9360:2012 [35] to monitor the settlement of the foundation of the high-rise buildings. Under this Standard, measuring the settlement is divided into three levels: level I, level II and level III. 2.1.4.2. Settlement monitoring cycle Settlement monitoring cycle in the foundation and basement construction process is determined based on the construction progress. 2.2. Monitoring the settlement of the foundation of the high-rise buildings in the foundation and basement construction period by the surveying method 2.2.1. Structure of landmark for monitoring the settlement of the foundation and basement of the high-rise buildings 2.2.2. Designing the monitoring network system The system of settlement monitoring height network is designed with two levels: basic height network and monitoring network. 2.2.3. Monitoring settlement of the ground base surrouding the foundaiton pit Height of the point of monitoring the settlement of the ground base surrounding the foundation pit should be measured by the high geometric measurement method with accuracy in accordance with settlement measure level III. 5 2.2.4. Monitoring settlement of the works adjacent to the excavated holes Measuring the settlement of the adjacent works (residents’ houses, steel-enforced concrete works) should be conducted with accuracy in accordance with settlement measure level II. 2.2.5. Monitoring emerging of the foundation pit Height of the point of monitoring the emerging deformation of the foundation pit should be measured by the high geometric measurement method with accuracy in accordance with settlement measure level III. 2.2.6. Monitoring the settlement of the main work in the basement construction process In nature, monitoring the settlement of the main work means monitoring the settlement of the diaphragm wall (basement wall) and internal parts of the diaphragm wall (column, partition, lifter wall, etc.). Accuracy in measuring the settlement of the main work should follow the accuracy of measuring the settlement level II. 2.2.7. Processing the settlement monitoring data of the foundation of the high-rise buildings in the foundation and basement construction period 2.2.7.1. Analysis of stability of basic height mark Standard on stability of basic height mark: S i 2 m | S | t. 1k (2.15) In formula (2.15): S i - settlement of the basic height point in the current cycle in comparison with the first cycle; m S - requirement on accuracy in settlement determination; ; t: coefficient for determining and correcting limit error (t = 2÷3); k - accuracy attenuation coefficient between network levels (k = 2÷3). 2.2.7.2. Calculation of adjustment of the settlement monitoring height network 2.2.7.3. Calculation of work settlement parameter 2.2.8. Comment on monitoring the settlement of the foundation of the high-rise buildings by the surveying method The surveying method has the advantage of high accuracy, giving absolute settlement value. The disadvantage of this method is that in order to monitor settlement of the soil layers in line with their depths (monitoring settlements of the foundation soil layers), it is required to execute separate monitoring marks. Thus, the installation takes huge effort and each depth needs to be monitored requires a separate boring hole for installing mark. 2.3. Monitoring the settlement of the foundation of high-rise buildings in the construction period using sensing 2.3.1. Structure of magnetic extensometer system Magnetic extensometer is a specialized device for monitoring settlement in compliance with the magnetic induction principle. The magnetic extensometer system consists of: guide pipe, standard magnet, spider magnet, plate magnet, meter wire and magnetic probe. 6 Figure 2.9. Measuring settlement by magnetic extensometer P O O P H = H + L - L (2.18) In which: H P : Height of P; H o Height of bottom mark (benchmark height); L o : Distance between pipe top and bottom mark; L P : Distance from pipe top to the monitoring point P. The settlement value of the monitoring point is determined by comparising its heights in two various measurement cycles. 2.3.4. Accuracy in measuring settlement by magnetic extensometer method According to Document [14], settlement square error is determined by magnetic extensometer technology achieving size (5 8) mm. 2.3.5. Example on measuring settlement of the work foundation by magnetic extensometer 2.3.6. Comment on monitoring settlement of the foundation of high-rise buildings by sensing The method of using sensing (magnetic extensometer) has the advantage that it permits arranging many monitoring marks for various depths at each boring hole. The disadvantage of this method is that it takes the point at the pipe bottom as benchmark. Thus, it is required that the bottom of the guide pipe to be anchored into stable rock layer lying at depth (not be settled). If this rock layer locates too deeply, it will be difficult for installing and it is not economical for boring deeply. On the other hand, it is impossible to evaluate the stability of the reference point in each monitoring cycle. Therefore, if the reference point is settled, then the settlement value obtained at the settlement measuring table will not reflect the settlement of the monitored soil layers accurately. 2.4. Solution in combining the method of surveying and using sensing for monitoring the settlement of the foundation of high-rise buildings To overcome the disadvantage of the method of surveying and using sensing, this Dissertation suggests combining these two methods together to monitor the 2.3.2. Installation method Guide pipe with spider is installed in boring hole and arranged in sequence as shown in Figure 2.9. 2.3.3. Principle on measuring settlement by magnetic extensometer In magnetic extensometer method, point at the pipe bottom is taken as benchmark and height of the monitoring point is determined as follows (Figure 2.9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Magnetic probe Plate magnet Spider magnet Datum magnet Filling soil Original rock L 0 L P A P 1 O P n P i Meter wire 7 settlement of the soil layers and emerging of the foundation pit. The combining process is executed as follows: 2.4.1. Bottom of the guide pipe is anchored into a stable rock layer Closing error of monitoring settlement by magnetic extensometer ( ) is calculated by the following formula: Δ §T T§ = S - S (2.19) In formula (2.19): S ĐT - settlement of pipe top (Point A - Figure 2.9) measured by magnetic extensometer; S TĐ - settlement of pipe top measured by surveying method. Distributing the closing error ( ) for the measuring points at the depth in line with the principle of direct proportion to the distance from the pipe bottom to the measuring point will be able to determine the settlement values at the settlement measuring tables with increased accuracy (formula 2.20). Δ i ii OP §T PP OA .L S = S - L (2.20) In which: i §T P S : settlement of Poin P i measured by magnetic extensometer; i OP L : distance from the point at the pipe bottom to the monitoring point P i ; OA L : distance from the point at the pipe bottom to the monitoring point A at the pipe top. 2.4.2. Bottom of the guide pipe is anchored into an unstable rock layer For this case, the value ( ) that is obtained using formula (2.19) could be considered as the settlement of the reference point at the pipe bottom. At that time, adjust the value ( ) for the measuring points at the depth by following formula: Δ ii §T PP S = S - (2.21) Also in this case, it is possible to use the point at the top of tube as a reference point. Elevation of the reference point is determined by surveying method (often, geometric leveling). 2.4.3. Example on measuring the foundation settlement by the method of surveying and magnetic extensometer 2.4.3.1. Example in case bottom of the guide pipe is anchored into a stable rock layer 2.4.3.2. Example in case bottom of the guide pipe is anchored into an unstable rock layer 2.4.4. Comments on monitoring settlement of the foundation of high-rise buildings by combing the method of surveying and using sensing The solution in combining the method of surveying and using sensing (magnetic extensometer) for monitoring the settlement of the foundation of high-rise buildings have the following meanings: - To increase the accuracy in measuring settlement at the settlement monitoring tables (in case bottom of the guide pipe is anchored into a stable rock layer) - To permit taking the point at the pipe top as benchmark for determining settlement at the settlement monitoring tables. So, in this case, the guide pipe should not be anchored into the stable rock layer; it is only necessary to install the guide pipe to the depth of the soil layer that needs monitoring settlement. Thus, it will be more convenient for constructing and installing the guide pipe, allowing increasing the effectiveness of monitoring the settlement of the foundation of high-rise buildings. 8 Chapter 3. MONITORING DISPLACEMENT OF THE DIAPHRAGM WAL OF THE HIGH-RISE BUILDINGS IN THE FOUNDATION AND BASEMENT CONSTRUCTION PERIOD 3.1. Technical requirements on monitoring displacement of the diaphragm wall of high-rise buildings 3.1.1. Some general concepts of constructing the foundation and basement of high-rise buildings 3.1.1.1. Measures in constructing the basement of high-rise buildings 3.1.1.2. Measures in obstructing soil for excavating hole in the foundation and basement construction process 3.1.1.3. Diaphragm wall of high-rise buildings 3.1.2. Causes of displacement and deformation of the diaphragm wall In the process of excavating holes for constructing the foundation and basement, when some soil volume is taken, the stress status will be changed. This leads to deformation of the soil block surrounding the excavated holes. Soil will displace to the excavated holes, which could make the diaphragm wall displace. 3.1.3. Purpose of monitoring displacement of the diaphragm wall Monitoring displacement of the diaphragm wall is aimed at determining displacement and deformation extent; researching to find the cause of displacement and deformation of the diaphragm wall; thereby, taking the measure for treating, preventing the accident occurring to the work and adjacent works. 3.1.4. Requirements on accuracy and cycle of monitoring displacement of the diaphragm wall 3.1.4.1. Requirement on monitoring accuracy Method 1: Based on the predicted displacement value (provided by the designing unit) to determine the requirement on monitoring accuracy. Method 2: It is possible to use the displacement measurement levels in Vietnamese Standard TCVN 9399:2012 “Buildings and civil structures - Measuring horizontal displacement by surveying method” [38] to monitor the displacement of diaphragm wall. 3.1.4.2. Cycle of monitoring displacement of the diaphragm wall Monitoring cycle depends on the construction progress of the excavated hole. 3.2. Monitoring displacement of the diaphragm wall by the surveying method 3.2.1. Designing structure and distributing benchmark for monitoring displacement of the diaphragm wall 3.2.2. Designing the network system for monitoring displacement of the diaphragm wall The system of monitoring displacement network of the diaphragm wall is designed with two levels: basic and monitoring level. The requirement on errors in determining the placement for the network levels is determined by the following formulas: - For basic network: CS q q 2 m m = 1k (3.3) [...]... solution in combining these two methods to increase the effectiveness of monitoring deformation of the foundation and basement of high- rise buildings in the construction period 2 /The work deformation model is developed based on the monitoring data which permit analyzing settlement as well as displacement of the foundation, diaphragm wall of high- rise buildings chronologically, in space and evaluating the. .. ICL 3.4.3 Comments on monitoring the displacement of the diaphragm wall using the method of surveying and using sensing The solution in combining the method of surveying and using the sensing mentioned above permits determining the absolute displacement of the monitoring points at various depths of the diaphragm wall In this solution, the bottom of the guide pipe measured by Inclinometer does not need... in measurement and calculation errors caused by people 4/ADFB data processing software is completely sufficiently reliable to solve basic tasks of the process of analyzing, evaluating displacement of the foundation and diaphragm wall of high- rise buildings 2 Recommendations 1 /The data on monitoring deformation of the foundation and basement of highrise buildings in the construction period should be... to be anchored into stable rock layer However, for monitoring the diaphragm wall, the guide pipe need be installed equally to the depth of the diaphragm wall to obtain the monitoring data from the bottom to the top of the diaphragm wall 15 Chapter 4 ANALYSIS OF THE DEFORMATION OF THE FOUNDATION AND BASEMENT OF HIGH- RISE BUILDINGS IN THE CONSTRUCTION PERIOD 4.1 Principles on developing the work displacement... Experiment in monitoring the displacement of the diaphragm wall of the building by the automatic monitoring system The experiment process was conduced for the diaphragm wall of a high- rise building in Ba Dinh District - Ha Noi City This building has two basements The method of excavating the hole for constructing the foundation and basement is to excavate openly; the support for the wall of the excavated... develop the model using the main elements 4.2 Model on foundation settlement and diaphragm wall displacement in space 4.2.1 Model on foundation settlement of high- rise buildings in the foundation and basement construction period 4.2.1.1 Settlement model of solid foundation structure For solid foundation structure, when the settlement monitoring points are distributed in a wide range, use the plane equation... monitoring of fender of the high- rise building”, Building science and technology journal, No.3/2012, ISSN 1859-1566, Hanoi 5 Tran Ngoc Dong, Doan Duc Nhuan (2012), Research using the combination of Total Station and Inclinometer for monitoring the displacement of fencing wall of high- rise buildings , Summary of reports of the Science Conference on Young Officers - Institute for Building Science and Technology... accuracy 5.2 Experiment in developing the foundation settlement model of high- rise buildings in the foundation and basement construction period 5.2.1 Experiment in developing the settlement model for the foundations of Office No 22-24-26 Mac Thi Buoi, Ho Chi Minh City Based on the settlement monitoring data (coordinates, settlement and settlement mean square errors) of 14 settlement monitoring marks [40],... value of the foundation on the underground water based on the data on monitoring 37 cycles in the excavating process for constructing the foundation and basement for a real work [42], [43] The obtained data in each cycle consist of: monitoring time, underground water height and settlement value of each monitoring mark BM15 By using ADFB software, obtain final results as follows: 0.68 1 Correlation coefficient:... accuracy In the model development process, it is necessary to analyze the adjustment to evaluate the reliability of the model 24 CONCLUSION AND RECOMMENDATION 1 Conclusion 1 /The Dissertation has analyzed the characteristics of the method of surveying, using sensing in monitoring settlement, displacement of the foundation and basement of high- rise buildings Additionally, the Dissertation has suggested the . Scope of research of the dissertation consists of: Researching the method of surveying, using sensing to monitor the deformation of foundation and basement of the high-rise buildings; Researching. basement of the high-rise building in the construction period. - Object of research is: the method of monitoring, analyzing deformation of foundation and basement of high-rise buildings in Vietnam MONITORING THE DEFORMATION OF THE FOUNDATION AND BASEMENT OF HIGH-RISE BUILDINGS IN THE CONSTRUCTION PERIOD 1.1. Overview of foreign research works 1 - Monitoring the displacement of the foundation