| Landslide has the characteristics of sudden happening, enormous destructive power, and often pose a serious threat to the lives and property of residents of the landslide area. In recent decades, with the human activities become increasingly frequent, landslide disasters are becoming more frequent, and the losses are also growing. Moreover, some landslides are triggered with strong concealment, and without the aid of advanced monitoring equipment, it is difficult to find the security risks. In order to effectively prevent or mitigate loss of landslides, domestic and foreign scholars have done a lot of tests and practical research, and has made a series of significant results on cognition, discovery, monitoring, forecasting, and control. Throughout the research and development process of the landslide, reliable means of monitoring have always been the basis of other research aspects. Effective and accurate monitoring and early forecasting are also effective ways to decrease losses and casualties.In China, landslide hazards are widespread, and for all segments including engineering control, mechanism research, forecasting and other problems to be solved, almost all the work will depend on landslide monitoring data to be carried out. Nonetheless, the development of domestic landslide monitoring instruments and monitoring methods fall behind the newest technology in the world. Therefore, it has significant scientific and engineering significance to work on the landslide monitoring equipment development, explore the monitoring measures and investigate the methodology of monitoring data.There are numerous factors influencing the landslide, thus the monitoring objects can also be very broad. However, the displacement has always been the vital and indispensable monitoring object. The displacement monitoring of landslide is a supportive research task for landslide research, providing an intuitive quantitative reference data for the mechanism analysis, engineering control, forecasting, etc. Among them, monitoring of deep displacement is an important part, involving displacement measuring principle, measuring method, instruments, and data processing. This paper focus on the deep displacement monitoring and analysis, and systematic research has been carried out on the measurement principle analysis, coupled deformation analysis of tube and soil, quantization of corresponding relations of displacement and external factors, and the synthetic applications of the research achievements. The main research contents and results are as follows:(1) The inertial measurement principle is analyzed and introduced based on the requirements of landslide deep displacement measuring environmental. The basic principle of inertial measurement system is to sense the line and angular movement relative to the inertial space by using the inertial device, then the measurement results will be calculated on the time axis, and finally the linear velocity, attitude angle and position information can be obtained. The process of measurement does not depend on any external sound, light, electricity, magnetism or other information, neither requires external radiation signal. It is a fully autonomous, extremely closed and real-time measurement system. However, compared with the resolution of the inertial measurement system, the landslide slipping velocity is much smaller than the resolution magnitude of the system, so the system can not inertial measure the landslide movement directly. Corresponding way is proposed to resolve this question, which is burring the deformation coupled pipes in the landslide body for coupling landslide deformation, thus it converts the accumulated displacement versus time into deformation along the pipeline. Therefore, the amount of landslide displacement can be obtained only by measuring the pipeline track in time segments. Traditional inertial measurement systems have obvious functional and structural redundancy, which is not conducive to the measurement. According to characteristics of measured environment, the function and structure of the inertial measurement system are simplified, and the access for some physical parameters (such as line speed and position along the pipe) is converted to contact measurement.(2) For deep displacement in the landslide, the horizontal displacement is the dominating displacement, and there is no need to considerate the vertical direction distribution, based on which the vertical distribution of horizontal displacement measuring instruments (flexible inclinometer instrument) is developed. Based on the acceleration of gravity, and the principle of measuring angles by measuring gravitational component through accelerometers, two-axis angle measurement unit is designed. Then the measurement units are linked in series and be infusion packaged using silica, until it forms a flexible inclinometer detector. Meanwhile, the matched controller and supporting PC software are designed. To verify the designed prototype in the lab, the flexible probe is placed in the vertically stationary graph paper, then reading out the shape and position of the probe and compare with the measured data. The results show that measurement has the best displacement calculation errors, and for a 400 mm long probe tip, mean square deviation of displacement is less than 1.17 mm. Flexible inclinometer is ideal for lab physical model tests, can also be installed in the field for in-situ monitoring with the support of auxiliary support substrate.(3) For lateral slope swinging displacement, it is usually negligible, and this device mainly considers the lateral displacement component of the main sliding direction, and transverse displacement distribution measuring instrument (lateral track instrument) is developed. Combined with the requirements of lateral deformation pipe coupling track measurement, the instrument scheme is made comparison and demonstration, in which the required parameters to be measured are horizontal azimuth, pitch angle, roll angle and line speed along the pipe. Contraposing to the required physical measurements, the combination of "single-axis gyro+ two-axis accelerometer+ external wheel encoders" is used, which is half strapdown and semi-platform structure. The instrument design includes mechanical structure, hardware circuit control program and track algorithm. For the track algorithm, as the pipe axis linear acceleration will have certain impact on the pitch angle accelerometer, compensation from the axial velocity can eliminate uneven traction the error caused in the depth direction.(4) The pipe-soil interactive mathematic model is established referring to the ground settlement analog model. Following the D-P (Drucker-Prager) principle, the mechanical pattern, stress distribution and strain distribution of the pipe-soil interaction are simulated by finite element method program, ANSYS. In the mathematic model, the main assumptions include the non-linear property of the landslide geological body, the linear property of the pipe, the Ducan-Chang non-linear soil constructive model, the Boussinesq solution, and the pipe-soil coupling mechanical model based on pipe linear elastic equation. The relative pipe displacement to the soil in the coupling deformation, i.e., the error in the measurement of displacement by the pipe, is deduced on the pipe-soil interactive mathematic model. The results in the ANSYS indicates the following facts, the post-pipe soil is under compression, while the pre-pipe soil is under shearing; on the axial direction of the pipe, the compressive and shearing stress in the soil decreases when shallow buried; the corresponding soil elastic compressive and shearing strain shows the same pattern.(5) The selective principle of the coupling pipe and the displacement error compensations are proposed based on the pipe-soil interactive mathematic model and the simulative model. The selected pipe is recommended to be of smaller flexural stiffness and higher radial compressive strength simultaneously. The radial size of the pipe is suggested to be bigger while considering the cast and craft. In the practical use, the ancillary anchoring structure can increase the radial pipe pressed area, aimed to improve the coupling deformation. Following the selective principle of the pipe, the proper coupling pipe is easy to find. Thusly, the pipe selection is suggested to be taken as the priority, avoiding compensating the displacement error in the mathematical model.(6) The displacement mode of soil landslide is discussed and geological characteristics and monitoring data of Majiagou No.1 landslide is considered to summarize the displacement principle influenced by external factors. According to the mode of action, the displacement factors are divided into internal and external factors. The internal factor is related to material composition, geological characteristics and physical and mechanical parameters, which are difficult to obtain; the external factor is always associated with the external environment, which is easy to monitor. For analysis, the internal factors are packaged as a black box, which is taken as a displacement response system under the influence of external factors, and the focus is to analyze the mapping between displacement and external factors. Comparison of rainfall and water level parameters of Majiagou No.1 landslide and its GPS displacement monitoring data are made with the corresponding period, it is clear that the rainfall parameters and displacement are positively correlated, with the water level negatively correlated. In response to the external factors, displacement characteristics shows a time delay, input saturation and that different factors counts different proportion of effect, and this phenomenon is various in different locations of landslide.(7) Based on the influence of external factors on landslide displacement, the mapping principle between landslide displacement and external factors are made. On the basis of conventional landslide displacement prediction mode, the input of external factors is quantified, and the quantifiable indicators are response delay time τ and input saturation parameter s. The quantization basis is the presence of certain linear relation between displacement and external factors, then the correlation coefficient is introduced as a quantization criterion to judge the rationality of the values, thereby to obtain the quantization parameter values that have the greatest correlation. Different positions of landslide have distinctive response on external factors, consequently, the quantification analysis is only suitable for a single monitoring point, or to the monitoring group that has similar deformation amount and principle.(8) Summary of the research results is made based on the application process of landslide displacement monitoring and analysis. Taking landslide displacement monitoring and analysis as the primary task, the monitoring project management, coupled deformation analysis and quantitative analysis of displacement are collected into the developed PC software. The data acquisition terminal is connected to the instrument, then landslide displacement data will be read or imported into the instruments. After compensation of deformation compatibility analysis, the displacement and rainfall and water level will be introduced into quantitative analysis module, finally the quantified analysis report will be generated.(9) Combined with the laboratory physical model test, applications in the physical model test and field are described for the flexible inclinometer. The flexible inclinometer has excellent flexural deformation capacity, and can withstand a certain degree of longitudinal elongation, which is generally applicable for real-time monitoring on landslide model test in deep displacement with s or no piles. The flexible inclinometer can be directly attached on the surface of the front and rear walls of stabilizing pile to monitor the displacement of piles caused by landslides deformation. Also it can be directly buried in the landslide, to monitor the internal displacement distribution of the landslide; by the comparison between physical model test pile test results with stabilizing pile and the model sectional cracks, the feasibility and accuracy of the inclinometer in the physical model test is verified. In addition, the flexible inclinometer is also applicable for the landslide site monitoring, while the installation process requires reinforcement plate (it can be stabilizing piles) for positioning.(10) With the combination of Majiagou No.1 landslide test site, the application of lateral trajectory of instrument and the system is described in landslide lateral displacement measurement. In the Majiagou No.1 landslide, the 170m elevation is selected as pipe location based on the landslide morphology and composition of matter. The type of pipe and piping process is introduced, and after the burry of the pipeline, the initial position and trajectory are determined. As the piping process is short, no clear track difference has been formed yet, thus the displacement data can also not be obtained. Consequently, by means of the conventional GPS displacement monitoring data, demonstration for quantitative analysis of the system is made. The data of Majiagou to No.l landslide J01 monitoring site is analyzed with the quantization process. As shown by the results, the correlation coefficient of J01 monitoring site by the impact of rainfall parameters is 0.44903, and response time to the rainfall parameter delays 10 days, with monthly rainfall input saturation value 78 mm/month. J01 monitoring site is primarily affected by water level fluctuations, with the correlation coefficient -0.70655, and the response time to the decline of the water level rate delays 77 days, and the rate of water level in the observed period of time does not reached saturation.The primary innovation points of this dissertation are summarized as follows:(1) Introduction and principle match of inertial measurement systems with landslide displacement monitoring. Embedded pipes are proposed to couple landslide deformation. By measuring the three-dimensional track deviation of embedded pipes, the landslide displacement field is reflected; the measurement method can be used to arrange survey line be in any direction and depth in landslide body. While according to the measuring principle, landslide measurement environment and instrument cost, it is better to divide the measurement into the vertical displacement measuring and the lateral displacement measuring, therefore the inertial measurement principle is best matched with the specific measurement form.(2) The pipe-soil coupled deformation analysis. Based on the application environment of landslide displacement measurement, the forces of the pipes and the soil is analyzed, then the deformation difference between the pipe and the soil is calculated, which can provide a reference for the displacement compensation and selection of engineering pipelines.(3) Quantitative analysis between external factors and displacement of the landslide. Based on the different responses on external factors from different positions of the landslide, this paper puts forward quantitative index of specific time delay for the specific location of the landslide and he saturation threshold value. Correlation coefficient is set to calculate index, and programming calculation is done to realize the quantitative process and calculate the index. |
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