Method and device for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion

Abstract

The present invention belongs to the field of geotechnical earthquake engineering technology, and specifically relates to a method and device for analyzing the probability risk of liquefaction lateral displacement of a site induced by long-lasting earthquake motion. The method comprises: step 1, obtaining long-lasting earthquake motion data; step 2, establishing a micro-inclined site model containing a liquefiable soil layer; step 3, inputting the data of step 1 into the model of step 2 for nonlinear dynamic response analysis, and monitoring the lateral displacement time history; step 4, using the selected local earthquake intensity parameters as candidate parameters, fully considering the predictability of the parameters, and identifying the optimal vector earthquake intensity parameters for the evaluation of liquefaction lateral displacement induced by long-lasting earthquake motion from the candidate parameters; step 5, using the optimal vector earthquake intensity parameters and site parameters as variables, a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion is proposed; step 6, based on the model of step 5, the annual average exceedance rate density of the optimal vector intensity parameters is calculated, and then the liquefaction lateral displacement hazard curve is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical earthquake engineering, and in particular relates to a method and device for analyzing the probability risk of liquefaction lateral displacement of a site induced by long-lasting earthquake motion. Background Art

[0002] When a liquefiable site is subjected to earthquake loads, it is usually accompanied by significant settlement, tilting, and lateral displacement, which will cause serious damage to the buildings or structures on the site. For a slightly tilted liquefiable site, due to the existence of initial static shear stress, the strength and stiffness of the soil decreases sharply under the action of an earthquake, so it is easy to induce liquefied lateral displacement. The liquefied lateral displacement induced by the 2008 Wenchuan earthquake caused large deformation and damage to the Baihua Bridge in Yingxiu Town; the liquefied lateral displacement induced by the 1995 Hanshin Earthquake in Japan caused the concrete caisson pier wall to move 5 meters toward the sea. Therefore, accurate evaluation of liquefied lateral displacement is of great significance for reducing and preventing liquefaction-induced disasters.

[0003] In the past two decades, many large-magnitude earthquakes have occurred one after another, such as the 2008 Wenchuan earthquake (8.0 on the Richter scale), the 2010 Concepción earthquake in Chile (8.8 on the Richter scale), and the 2011 Japan 3.11 earthquake (9.0 on the moment magnitude scale). These large-magnitude earthquakes have longer durations than ordinary ground motions, and the source fault area is larger, releasing more energy, and often cause more serious liquefaction disasters. The existing liquefaction lateral displacement prediction models have not conducted relevant research on long-lasting ground motions. With the increase in the frequency of long-lasting ground motions in recent years, the impact of long-lasting ground motions cannot be ignored in the evaluation of liquefaction lateral displacement. In order to more accurately evaluate the liquefaction disaster caused by long-lasting ground motions on the site, it is necessary to comprehensively consider the uncertainty of long-lasting ground motion loads and their induced liquefaction lateral displacements, so as to provide a reference for the evaluation of site liquefaction-induced disasters. Therefore, it is necessary to develop a risk analysis method for evaluating the liquefaction lateral displacement of a specific site when it is subjected to long-lasting ground motions in an efficient, accurate and rapid manner. Summary of the invention

[0004] The present invention is made to solve the above-mentioned problems, and its purpose is to provide a method and device for analyzing the probabilistic risk of lateral displacement of site liquefaction induced by long-lasting earthquake motion, which can accurately, quickly and efficiently estimate the risk of lateral displacement caused by liquefaction when the site is subjected to long-lasting earthquake motion, and provide reliable data for disaster assessment induced by site liquefaction.

[0005] In order to achieve the above object, the present invention adopts the following scheme:

[0006] <Method>

[0007] The present invention provides a method for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake, comprising the following steps:

[0008] Step 1, according to the duration characteristics of earthquake motion, selecting earthquake motions with a significant duration greater than or equal to a duration threshold from the earthquake motion database as long-duration earthquake motion data for input;

[0009] Step 2: Use finite element software to establish a slightly inclined site model containing a liquefiable soil layer. When establishing the site model, it is necessary to fully consider the influence of the depth of the groundwater level, the inclination of the site, the thickness of the liquefiable layer and the anti-liquefaction performance on the site liquefaction triggering and the consequences of liquefaction lateral displacement; calibrate the selected soil parameters to ensure the correctness of the parameters;

[0010] Step 3, inputting the long-duration earthquake data selected in step 1 into the micro-inclination site model established in step 2 to perform nonlinear dynamic response analysis, monitoring and recording the pore water pressure ratio in the middle of the liquefiable soil layer and the lateral displacement time history of the site surface;

[0011] Step 4: Select the vibration intensity parameters of various places as candidate parameters. Based on the data monitored and recorded in step 3, take full account of the predictability of the parameters and select the candidate parameters [IM i ,IM j ], the optimal vector earthquake intensity parameters [IM1, IM2] for the evaluation of long-lasting earthquake-induced liquefaction displacement were identified;

[0012] Judging from the predictability of the parameters, the total transmission error is:

[0013]

[0014] Where: LD is the lateral displacement induced by liquefaction under long-lasting ground motion, IM i and IM j are two different earthquake intensity parameters among the alternative intensity parameters, is the standard deviation of the linear regression, b and c are the slopes of the linear regression, and IM i and IM j The standard deviation in the earthquake prediction equation; ρ[ln(IM i ),ln(IM j )] is the correlation coefficient between the two intensity parameters; the total transmission error σ ln(LD)|M,R The smaller the value, the better the predictability of the intensity parameter;

[0015] Step 5, using the optimal vector earthquake intensity parameters and site parameters as variables, a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion is proposed;

[0016] Step 6, based on the liquefaction displacement prediction model of step 5, according to the earthquake magnitude of the site, the distribution function of the focal distance, the fault type and the earthquake motion prediction equation of the optimal intensity parameter, the annual average exceedance rate density of the optimal vector intensity parameter is calculated, and then the liquefaction displacement hazard curve is obtained;

[0017] Annual average exceedance rate density of optimal vector intensity parameters

[0018]

[0019]

[0020]

[0021] In the formula, and are the median and standard deviation of the intensity parameter IM1 calculated by the earthquake motion prediction equation at a given magnitude m and focal distance r; and are the mean and standard deviation of IM2 given z1, m and r respectively;

[0022] The annual average exceedance rate density of intensity parameters IM1 and IM2 is convolved with the conditional probability of liquefaction lateral displacement LD when IM1 = z1 and IM2 = z2 to obtain the annual average exceedance rate of liquefaction lateral displacement LD:

[0023]

[0024] Wherein, P[LD>x|IM1=z1,IM2=z2] represents the probability that the lateral displacement is greater than x when IM1=z1 and IM2=z2.

[0025] Preferably, in the method for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake provided by the present invention, in step 1, a significant long-lasting earthquake D is selected. s5-75 Earthquake motions of 25 seconds or longer are used as long-duration earthquake motion data for input.

[0026] Preferably, in the method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting seismic motion provided by the present invention, in step 2, the soil parameters include: relative density, modulus, shear contraction and expansion coefficient of the soil; the geometric parameters include: soil layer distribution, depth of groundwater level, inclination of the site, thickness and position of liquefiable soil layer, thickness of covering layer, and inclination of the site.

[0027] Preferably, in the method for analyzing the probability risk of lateral displacement of site liquefaction induced by long-duration earthquake provided by the present invention, in step 4, the earthquake intensity parameters include parameters related to the duration and amplitude of the earthquake and the energy of the earthquake, and the earthquake intensity parameters are combined in pairs to form vector intensity parameters, and the earthquake intensity parameters that meet the effectiveness and sufficiency are selected to form candidate parameters [IM i ,IM j ].

[0028] Commonly used ground motion intensity parameters include ground motion duration (e.g., significant duration D s5-95 and D s5-75 ), amplitude (such as: peak ground acceleration PGA and peak ground velocity PGV) and ground motion energy (such as: Arias intensity I a and parameters related to the cumulative absolute velocity (CAV).

[0029] Specifically, in the method for probabilistic risk analysis of site liquefaction lateral displacement induced by long-lasting earthquake motion provided by the present invention, the liquefaction lateral displacement prediction model in step 5 is:

[0030] ln(LD)=a1×ln(IM j )+a2×[ln(IM j )] 2 +a3×ln(IM i )+a4×ln(Dr)+a5×ln(H L )+a6×ln(S)+a7×[ln(S)] 2 +a8

[0031] Where CAV is the optimal vector intensity parameter, Dr is the relative density of the liquefiable layer, and H L is the thickness of the liquefiable layer, S is the site inclination, and a1~a8 are constants to be solved.

[0032] Specifically, the method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion provided by the present invention, in step 5, takes the optimal strength parameter and site parameter as variables, and proposes a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion through the method of multivariate linear regression; in step 6, the magnitude of the site, the distribution function of the focal distance, and the fault type are obtained by statistically studying the magnitude, focal distance distribution, and fault type of earthquakes that have occurred in the past around the site.

[0033] <Device>

[0034] Furthermore, the present invention also provides a device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake, which can automatically control and implement the above <method>, comprising:

[0035] A long-duration data acquisition unit selects, from the earthquake database, earthquake motions with a significant duration greater than or equal to a duration threshold as long-duration earthquake motion data for input according to the earthquake motion duration characteristics;

[0036] The site model establishment department establishes a micro-inclined site model containing a liquefiable soil layer, determines the site parameters including geometric model parameters and soil parameters, and calibrates the soil parameters therein;

[0037] The monitoring and recording section inputs the long-term seismic data selected by the long-term data acquisition section into the micro-inclination site model established by the site model establishment section to perform nonlinear dynamic response analysis, monitor and record the pore water pressure ratio in the middle of the liquefiable soil layer and the lateral displacement time history of the site surface;

[0038] The identification unit selects the vibration intensity parameters of various places as candidate parameters, based on the data monitored and recorded in step 3, and fully considers the predictability of the parameters, and selects the candidate parameters [IM i ,IM j ], the optimal vector earthquake intensity parameters [IM1, IM2] for the evaluation of long-lasting earthquake-induced liquefaction displacement were identified;

[0039] Judging from the predictability of the parameters, the total transmission error is:

[0040]

[0041] Where: LD is the lateral displacement induced by liquefaction under long-lasting ground motion, IM i and IM j are two different earthquake intensity parameters among the alternative intensity parameters, is the standard deviation of the linear regression, b and c are the slopes of the linear regression, and IM i and IM j The standard deviation in the earthquake prediction equation; σ[ln(IM i ),ln(IM j )] is the correlation coefficient between the two intensity parameters; the total transmission error σ ln(LD)|M,R The smaller the value, the better the predictability of the intensity parameter;

[0042] The prediction model construction department proposes a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion, using the optimal vector earthquake intensity parameters and site parameters as variables;

[0043] The risk analysis department, based on the liquefaction displacement prediction model, calculates the annual average exceedance rate density of the optimal vector intensity parameter according to the site magnitude, the distribution function of the focal distance, the fault type and the earthquake motion prediction equation of the optimal intensity parameter, and then obtains the liquefaction displacement hazard curve;

[0044] Annual average exceedance rate density of optimal vector intensity parameters

[0045]

[0046]

[0047]

[0048] In the formula, and are the median and standard deviation of the intensity parameter IM1 calculated by the earthquake motion prediction equation at a given magnitude m and focal distance r; and are the mean and standard deviation of IM2 given z1, m and r respectively;

[0049] The annual average exceedance rate density of intensity parameters IM1 and IM2 is convolved with the conditional probability of liquefaction lateral displacement LD when IM1 = z1 and IM2 = z2 to obtain the annual average exceedance rate of liquefaction lateral displacement LD:

[0050]

[0051] Where, P[LD>x|IM1=z1,IM2=z2] represents the probability that the lateral displacement is greater than x when IM1=z1 and IM2=z2;

[0052] The control unit is connected to the long-term data acquisition unit, the site model establishment unit, the monitoring and recording unit, the identification unit, the prediction model construction unit, and the risk analysis unit to control their operations.

[0053] Preferably, the device for analyzing the probability risk of lateral displacement of site liquefaction induced by long-lasting earthquake motion provided by the present invention may also include: an input display unit, which is communicatively connected with the long-lasting data acquisition unit, the site model establishment unit, the monitoring and recording unit, the identification unit, the prediction model construction unit, the risk analysis unit, and the control unit, and displays corresponding information according to the operation instructions input by the user.

[0054] Preferably, in the device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake provided by the present invention, the input display unit can display the long-lasting earthquake data selected by the long-lasting data acquisition unit according to corresponding operation instructions, display the micro-inclination site model established by the site model establishment unit, display the data information monitored and recorded by the monitoring and recording unit, display the judgment of the identification unit and the identified optimal vector earthquake intensity parameters, display the liquefaction lateral displacement prediction model constructed by the prediction model construction unit, and display the annual average exceedance rate density solved by the risk analysis unit. The annual average exceedance rate of liquefaction lateral displacement LD is displayed.

[0055] Preferably, in the device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake provided by the present invention, the liquefaction lateral displacement prediction model in the prediction model construction part is:

[0056] ln(LD)=a1×ln(IM j )+a2×[ln(IM j )] 2 +a3×ln(IM i )+a4×ln(Dr)+a5×ln(H L )+a6×ln(S)+a7×[ln(S)] 2 +a8

[0057] Where CAV is the optimal vector intensity parameter, Dr is the relative density of the liquefiable layer, and H L is the thickness of the liquefiable layer, S is the site inclination, and a1~a8 are constants to be solved.

[0058] Functions and Effects of the Invention

[0059] (1) Compared with ordinary earthquake motion, long-lasting earthquake motion has a larger magnitude, a longer duration, and a greater number of cycles. The present invention comprehensively considers the overall uncertainty of the long-lasting earthquake motion prediction equation and the displacement prediction equation and the predictability of the vector intensity parameter, so as to minimize the prediction error and transmission error of the identified intensity parameter, and proposes the annual average exceedance rate density of the optimal vector intensity parameter based on the identified intensity parameter. The liquefaction lateral displacement probability risk curve is obtained by convolution based on the annual average exceedance rate density, which can quickly, accurately, and reliably analyze and predict the site liquefaction lateral displacement probability risk under the action of long-lasting earthquake motion;

[0060] (2) The present invention can provide a reference for the liquefaction disaster risk assessment of areas susceptible to long-lasting earthquakes and further improve the reliability of decision-making. Engineers can reasonably formulate anti-liquefaction measures for the site based on the results of the site liquefaction risk assessment;

[0061] (3) When an earthquake occurs, the present invention can be used to quickly evaluate the liquefaction lateral displacement of the site in the study area based on the intensity of the earthquake motion and the soil conditions and geometric dimensions of the site, thereby avoiding a large number of model tests and field tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a flow chart of a method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to an embodiment of the present invention;

[0063] Figure 2is the earthquake acceleration response spectrum involved in the embodiment of the present invention;

[0064] Figure 3 is the excess pore water pressure ratio r in the middle of the liquefied layer under the action of the Pingwu Muzuo wave of the Wenchuan earthquake involved in the embodiment of the present invention u and the LD time history diagram of the lateral displacement of the site surface;

[0065] Figure 4 is the regression standard deviation σ of each candidate strength parameter involved in the embodiment of the present invention ln(LD) Results (validity determination);

[0066] Figure 5 is the slope mean k of the regression residual, magnitude and focal distance involved in the embodiment of the present invention avg (adequacy determination);

[0067] Figure 6 is the total standard deviation σ of the alternative strength parameters involved in the embodiment of the present invention ln(LD)|M,R Outcome (predictability determination);

[0068] Figure 7 A comparison diagram of the prediction results of the liquefaction lateral displacement prediction model based on CAV and the numerical simulation results involved in the embodiment of the present invention;

[0069] Figure 8 It is a liquefaction lateral displacement probability risk curve based on a point earthquake source involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The specific implementation scheme of the method and device for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to the present invention is described in detail below with reference to the accompanying drawings.

[0071] <Example 1>

[0072] like Figure 1 As shown, the method for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake provided in this embodiment includes the following steps:

[0073] Step 1: Select 126 long-duration earthquake motions with complete records in the past 20 years from the NGA-West2 database of the Pacific Earthquake Engineering Center of the United States, the China National Earthquake Science Data Center, the CESMD strong earthquake database of the United States, and the Kik-net database of Japan, mainly including the 2008 Wenchuan earthquake, the 2010 Concepción earthquake in Chile, and the 2011 Japan 3.11 earthquake. The selected earthquake motions have a magnitude range of 7.2 to 9.0, a focal distance range of 17.3 to 362.7 km, and a response spectrum acceleration of Figure 2 shown.

[0074] Step 2, determine the parameters of the liquefiable site model, including the distribution of soil layers in the site, the thickness of the liquefiable soil layer and its location, the depth of the groundwater level, the thickness of the covering layer, the inclination of the site, the relative density of each soil layer, etc. In this embodiment, the groundwater level is 2m below the surface, the thickness of the liquefiable soil layer is set to 3m, 6m and 9m respectively, all located 2m below the surface, and the relative density of the liquefied soil layer is 40%, 50% and 60% respectively. Above the liquefied layer is a 2m thick dry sand covering layer, and the bottom is a dense sand layer. A total of 6 cases are considered for the site inclination, which are 0.1%, 0.5%, 1%, 2%, 3% and 4%, respectively, and the depth of the entire model is 20m. Subsequently, the open source finite element software OpenSees was used to model the slightly inclined site. The Lysmer-Kuhlemeyer sticky pot was applied to the bottom of the model to simulate the finite stiffness of the bottom soil. The boundaries on both sides were impermeable boundaries, and the nodes at the same height bound the displacement and pore pressure freedom; the bottom was an impermeable boundary with fixed vertical displacement; the top was a permeable boundary. Other soil parameters (such as shear modulus, bulk modulus, phase transition angle, and shear contraction and dilation coefficient, etc.) were calibrated according to the relative density of the liquefiable sand layer. In this embodiment, the CRR-N curve of the unit shear simulation test was compared with the CRR-N curve measured on site to perform parameter calibration.

[0075] Step 3: Convert the selected long-lasting earthquake acceleration time history into a stress time history and apply it to the bottom boundary of the model to perform nonlinear dynamic response analysis. In this embodiment, a total of 54×126=6804 dynamic response analyses were performed to monitor the excess pore water pressure ratio r in the middle of the liquefiable soil layer. u and the lateral displacement LD of the top of the site. Taking the dynamic response results of the Pingwu Muzuo wave analysis of the 2008 Wenchuan earthquake as an example, when the relative density of the liquefiable layer is 40%, the thickness is 6m, and the site inclination is 2%, r u The time course curve of LD is as follows Figure 3 shown.

[0076] Step 4: Perform linear regression analysis on the liquefaction lateral displacement and each alternative intensity parameter, and identify the optimal vector earthquake intensity parameter for the evaluation of long-term earthquake-induced liquefaction lateral displacement based on the effectiveness and sufficiency and the predictability criterion.

[0077] The logarithmic linear regression equation is used to describe the relationship between the liquefaction lateral displacement and each candidate vector intensity parameter:

[0078] ln(LD)=a+b×(IM1)+c×(IM2)+ε ln(LD)

[0079] Where: LD is the liquefaction-induced lateral displacement under long-lasting ground motion, IM1 and IM2 are alternative strength parameters, a, b and c represent regression coefficients, ε ln(LD)Represents the regression residual. Regression standard deviation σ ln(LD)|lnIM The smaller the value, the better the effectiveness of the strength parameter; the sufficiency is measured by the residual ε in the regression analysis. ln(LD) The dependence of magnitude on focal distance can be expressed as:

[0080] ε1=c1+k1×M w +ε Mw

[0081] ε2=c2+k2×R rup +ε Rrup

[0082] Where: M w Represents the magnitude, R rup represents the earthquake source distance, and represents the residual; c1, c2, k1, and k2 represent the regression coefficients; wherein, the smaller the regression coefficients k1 and k2 are, the better the sufficiency of the intensity parameter is.

[0083] In this embodiment, the commonly used intensity parameters of ground motion peak acceleration PGA, ground motion peak velocity PGV, Arias intensity I are selected respectively. a , Cumulative absolute velocity CAV, 70% energy significant duration D s5-75 The spectral acceleration values ​​Sa(0.5s) corresponding to 0.5s and Sa(1.0s) corresponding to 1.0s are combined in pairs as candidate strength parameters for evaluating the liquefaction displacement induced by long-term earthquake motion. The monitored site lateral displacement and strength parameters are subjected to logarithmic linear regression. The standard deviation results of regression for different sites are shown in Figure 2. Figure 4 As shown. In general, the regression standard deviation σ of the intensity parameter [PGV, CAV] ln(LD)|lnIM The smaller the value is, the better the effectiveness is among all the candidate intensity parameters. In addition, according to the dependence of regression residuals on magnitude and focal distance, the index k is used. avg To evaluate the adequacy of each candidate strength parameter:

[0084]

[0085] Where: k1 and k2 are the slopes of the regression of residuals on magnitude and focal distance, respectively. avg The smaller the value, the better the sufficiency of the intensity parameter. The vector intensity parameters with the best sufficiency are [CAV,D s5-75 ], the sufficiency determination results of each strength parameter are as follows Figure 5 shown.

[0086] On this basis, considering the error transfer of strength parameters from the earthquake motion prediction equation to the liquefaction lateral displacement equation, the predictability of the alternative strength parameters is judged, and the total standard deviation σ ln(LD)|M,RThe smaller its value, the better the predictability of the intensity parameter. The predictability judgment is based on the judgment results of effectiveness and sufficiency (alternative parameters), and only for σ ln(LD)|lnIM Less than 0.6, k avg The intensity parameters (selected candidate parameters) less than 0.15 were used for predictability judgment. There were 9 groups of vector intensity parameters that met the requirements. The predictability judgment results of these 9 groups of intensity parameters are as follows: Figure 6 As shown. Figure 6 As can be seen in , the parameter with the best predictability is [PGV, CAV], so it is identified as the optimal vector ground motion intensity parameter for liquefaction lateral displacement evaluation.

[0087] Step 5: Using the identified optimal strength parameters [PGV, CAV], according to the liquefaction lateral displacement results calculated by numerical simulation in step 3, and considering the influence of site inclination, liquefied layer thickness and relative density on lateral displacement, a liquefaction lateral displacement prediction model under long-term ground motion is proposed based on multivariate linear regression:

[0088] ln(LD)=3.736×ln(CAV)-1.071×[ln(CAV)] 2 -0.149×ln(PGV)-0.966×ln(Dr)+1.241×ln(H L )+0.444×ln(S)-0.136×[ln(S)] 2 +0.203

[0089] In the formula, CAV(gs) is the optimal ground motion intensity parameter, Dr(%) is the relative density of the liquefiable layer, H L (m) is the thickness of the liquefiable layer, S (%) is the site inclination. The predicted standard deviation is σ ln(LD) is 0.504, and the coefficient of determination R 2 The predicted results of the liquefaction lateral displacement prediction model based on [PGV, CAV] for lateral displacement are consistent with the lateral displacement results calculated by finite element numerical simulation. Figure 7 shown.

[0090] Step 6, statistically study the magnitude, focal distance distribution and fault type of historical earthquakes around the study site; based on the proposed liquefaction displacement prediction model, according to the site's magnitude, focal distance distribution function, fault type and the earthquake motion prediction model with the optimal intensity parameter, calculate the annual average exceedance rate curve of the optimal intensity parameter, and combine the proposed prediction model for long-lasting earthquake motion-induced liquefaction displacement to obtain the liquefaction displacement hazard curve.

[0091] In this embodiment, the point earthquake source is set to be 10 km away from the site. Considering the limitations of the existing earthquake motion prediction equation for predicting large-magnitude earthquake intensity parameters, the earthquake magnitude of the point earthquake source is set to 6.0 to 8.0 (with an interval of 0.1), and the fault type is set to a strike-slip fault. The annual occurrence rate of earthquakes above magnitude 6.0 in this earthquake source is 0.02. According to the optimal earthquake intensity parameters [PGV, CAV] identified in step 4, the annual average exceedance rate density MRD of [PGV, CAV] can be obtained based on the magnitude and source distribution function. PGV,CAV According to the proposed liquefaction lateral displacement prediction model, when PGV=z1, CAV=z2, the conditional probability that the lateral displacement is greater than x can be expressed as:

[0092]

[0093] In the formula, and σ ln(LD) are the mean and standard deviation of the lateral displacements calculated by the proposed lateral displacement prediction equation under long-lasting earthquake motion. Finally, the annual average exceedance rate density MRD of [PGV, CAV] is calculated. PGV,CAV By convolving with the conditional probability P[LD3x|PGV=z1,CAV=z2], we can obtain the lateral displacement risk curve of the site.

[0094] In this example, only the liquefaction lateral displacement probability risk curve is shown when the site inclination is 2%, the liquefiable layer thickness is 6m, and the relative density is 40%. Figure 8 As shown. When the relative density of the liquefiable layer is 40%, the liquefaction lateral displacement value of the site once in 475 years is 9.68m; the liquefaction lateral displacement value of the site once in 2475 years is 18.58m. Engineers can propose reasonable measures based on the calculated lateral displacement risk to reduce or avoid damage to overlying buildings and structures caused by lateral displacement of the site.

[0095] <Example 2>

[0096] The second embodiment of the present invention provides a device for analyzing the probability risk of lateral displacement of site liquefaction induced by long-lasting earthquake motion, which is capable of automatically implementing the above-mentioned method of the present invention. The device includes a sub-event generating unit, a magnitude determining unit, a source finite fault model determining unit, a function determining unit, a sequence generating unit, an input display unit, and a control unit.

[0097] The long-duration data acquisition unit is used to execute the content described in step 1 above, and selects earthquake motions with a significant duration greater than or equal to a duration threshold from the earthquake motion database as long-duration earthquake motion data for input according to the earthquake motion duration characteristics.

[0098] The site model establishment unit is used to execute the contents described in step 2 above, establish a micro-inclined site model containing a liquefiable soil layer, determine site parameters including geometric model parameters and soil parameters, and calibrate the soil parameters therein.

[0099] The monitoring and recording unit is used to execute the contents described in step 3 above, input the long-term seismic data selected by the long-term data acquisition unit into the micro-tilt site model established by the site model establishment unit for nonlinear dynamic response analysis, and monitor and record the pore water pressure ratio in the middle of the liquefiable soil layer and the lateral displacement time history of the site surface.

[0100] The identification unit is used to execute the content described in step 4 above, taking the selected vibration intensity parameters of various places as candidate parameters, based on the data monitored and recorded in step 3, taking full account of the predictability of the parameters, and selecting the candidate parameters [IM i ,IM j ] the optimal vector earthquake intensity parameters [IM1, IM2] for the evaluation of long-lasting earthquake-induced liquefaction displacement were identified.

[0101] The prediction model building unit is used to execute the content described in step 5 above, and proposes a liquefaction lateral displacement prediction model induced by long-lasting earthquake motion, taking the optimal vector earthquake intensity parameter and site parameters as variables.

[0102] The risk analysis unit is used to execute the contents described in step 6 above. Based on the liquefaction displacement prediction model, according to the earthquake magnitude of the site, the distribution function of the focal distance, the fault type and the seismic motion prediction equation of the optimal intensity parameter, the annual average exceedance rate density of the optimal vector intensity parameter is calculated, and then the liquefaction displacement hazard curve is obtained.

[0103] The input display unit is connected to the long-term data acquisition unit, the site model building unit, the monitoring and recording unit, the identification unit, the prediction model building unit, the risk analysis unit, and the control unit, and displays corresponding information according to the operation instructions input by the user. For example, the input display unit can display the long-term seismic data selected by the long-term data acquisition unit, the micro-tilt site model established by the site model building unit, the data information monitored and recorded by the monitoring and recording unit, the judgment of the identification unit and the identified optimal vector seismic intensity parameters, the liquefaction lateral displacement prediction model established by the prediction model building unit, and the annual average exceedance rate density solved by the risk analysis unit according to the corresponding operation instructions. The annual average exceedance rate of liquefaction lateral displacement LD is displayed.

[0104] The control unit is communicatively connected with the long-term data acquisition unit, the site model establishment unit, the monitoring and recording unit, the identification unit, the prediction model construction unit, the risk analysis unit, and the input and display unit to control their operations.

[0105] The above embodiments are merely examples of the technical solutions of the present invention. The method and device for analyzing the probability risk of lateral displacement of site liquefaction induced by long-lasting earthquake motion involved in the present invention are not limited to the contents described in the above embodiments, but are subject to the scope defined by the claims. Any modification, supplement or equivalent substitution made by technicians in the field of the present invention on the basis of this embodiment is within the scope of protection required by the claims of the present invention.

Claims

1. A probabilistic risk analysis method for lateral displacement of site liquefaction induced by long-lasting earthquake motion, characterized in that: The following steps are involved: Step 1, according to the duration characteristics of earthquake motion, selecting earthquake motions with a significant duration greater than or equal to a duration threshold from the earthquake motion database as long-duration earthquake motion data for input; Step 2, establishing a micro-inclined site model containing a liquefiable soil layer, determining site parameters including geometric model parameters and soil parameters, and calibrating the soil parameters therein; Step 3, inputting the long-duration earthquake data selected in step 1 into the micro-inclination site model established in step 2 to perform nonlinear dynamic response analysis, monitoring and recording the pore water pressure ratio in the middle of the liquefiable soil layer and the lateral displacement time history of the site surface; Step 4: Select the vibration intensity parameters of various places as candidate parameters. Based on the data monitored and recorded in step 3, take full account of the predictability of the parameters and select the candidate parameters [IM i ,IM j ], the optimal vector earthquake intensity parameters [IM1, IM2] for the evaluation of long-lasting earthquake-induced liquefaction displacement were identified; Taking into account the overall uncertainty of the long-term ground motion prediction equation and displacement prediction equation, the predictability of the parameters is judged and the total transmission error is: Where: LD is the lateral displacement induced by liquefaction under long-lasting ground motion, IM i and IM j are two different earthquake intensity parameters among the alternative intensity parameters, is the standard deviation of the linear regression, b and c are the slopes of the linear regression, and IM i and IM j The standard deviation in the earthquake prediction equation; ρ[ln(IM i ),ln(IM j )] is the correlation coefficient between the two intensity parameters; the total transmission error σ ln(LD)M,R The smaller the value, the better the predictability of the intensity parameter; Step 5, using the optimal vector earthquake intensity parameters and site parameters as variables, a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion is proposed; Step 6, based on the liquefaction displacement prediction model of step 5, according to the earthquake magnitude of the site, the distribution function of the focal distance, the fault type and the earthquake motion prediction equation of the optimal intensity parameter, the annual average exceedance rate density of the optimal vector intensity parameter is calculated, and then the liquefaction displacement hazard curve is obtained; Annual average exceedance rate density of optimal vector intensity parameters In the formula, and are the median and standard deviation of the intensity parameter IM1 calculated by the earthquake motion prediction equation at a given magnitude m and focal distance r; and are the mean and standard deviation of IM2 given z1, m and r respectively; The annual average exceedance rate density of intensity parameters IM1 and IM2 is convolved with the conditional probability of liquefaction lateral displacement LD when IM1 = z1 and IM2 = z2 to obtain the annual average exceedance rate of liquefaction lateral displacement LD: Wherein, P[LD>x|IM1=z1,IM2=z2] represents the probability that the lateral displacement is greater than x when IM1=z1 and IM2=z2.

2. The method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to claim 1 is characterized by: in, In step 1, select the significant duration D s5-75 Earthquake motions of 25 seconds or longer are used as long-duration earthquake motion data for input.

3. According to the method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion in claim 1, Features: Among them, in step 2, the soil parameters include: relative density, modulus, shear contraction and expansion coefficient of the soil; the geometric parameters include: soil layer distribution, depth of groundwater level, inclination of the site, thickness and position of liquefiable soil layer, thickness of cover layer, and inclination of the site.

4. The method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to claim 1 is characterized by: in, In step 4, the earthquake intensity parameters include parameters related to earthquake duration, amplitude and earthquake energy, and the earthquake intensity parameters are combined in pairs to form vector intensity parameters, and the earthquake intensity parameters that meet the effectiveness and sufficiency are selected to form candidate parameters [IM i ,IM j ].

5. The method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to claim 1, characterized in that: in, In step 5, the liquefaction lateral displacement prediction model is: ln(LD)=a1×ln(IM j (+a2×[ln(IM j )] 2 +a3×ln(IM i )+a4×ln(Dr)+a5×ln(H L (+a6×ln(S)+a7×[ln(S)] 2 +a8 Where LD is the liquefaction lateral displacement, Dr is the relative density of the liquefiable layer, and H L is the thickness of the liquefiable layer, S is the site inclination, and a1~a8 are constants to be solved.

6. The method for probabilistic risk analysis of lateral displacement of site liquefaction induced by long-lasting earthquake motion according to claim 1, characterized in that: in, In step 5, the optimal strength parameters and site parameters are used as variables, and a prediction model for liquefaction displacement induced by long-lasting ground motion is proposed through the multivariate linear regression method; In step 6, the magnitude of the site, the distribution function of the focal distance, and the fault type are obtained by statistically studying the magnitude, focal distance distribution, and fault type of earthquakes that have occurred in the past around the site.

7. A device for analyzing the probability risk of liquefaction lateral displacement of a site induced by long-lasting earthquake motion, characterized in that: include: A long-duration data acquisition unit selects, from the earthquake database, earthquake motions with a significant duration greater than or equal to a duration threshold as long-duration earthquake motion data for input according to the earthquake motion duration characteristics; The site model establishment department establishes a micro-inclined site model containing a liquefiable soil layer, determines the site parameters including geometric model parameters and soil parameters, and calibrates the soil parameters therein; A monitoring and recording unit, which inputs the long-duration seismic data selected by the long-duration data acquisition unit into the micro-inclination site model established by the site model establishment unit to perform nonlinear dynamic response analysis, and monitors and records the pore water pressure ratio in the middle of the liquefiable soil layer and the lateral displacement time history of the site surface; The identification unit selects the vibration intensity parameters of various places as candidate parameters, based on the data monitored and recorded in step 3, and fully considers the predictability of the parameters, and selects the candidate parameters [IM i ,IM j ], the optimal vector earthquake intensity parameters [IM1, IM2] for the evaluation of long-lasting earthquake-induced liquefaction displacement were identified; Taking into account the overall uncertainty of the long-term ground motion prediction equation and displacement prediction equation, the predictability of the parameters is judged and the total transmission error is: Where: LD is the lateral displacement induced by liquefaction under long-lasting ground motion, IM i and IM j are two different earthquake intensity parameters among the alternative intensity parameters, is the standard deviation of the linear regression, b and c are the slopes of the linear regression, and IM i and IM j The standard deviation in the earthquake prediction equation; ρ[ln(IM i ),ln(IM j )] is the correlation coefficient between the two intensity parameters; the total transmission error σ ln(LD)|M,R The smaller the value, the better the predictability of the intensity parameter; The prediction model construction department proposes a prediction model for liquefaction lateral displacement induced by long-lasting earthquake motion, using the optimal vector earthquake intensity parameters and site parameters as variables; The risk analysis department, based on the liquefaction displacement prediction model, calculates the annual average exceedance rate density of the optimal vector intensity parameter according to the site magnitude, the distribution function of the focal distance, the fault type and the earthquake motion prediction equation of the optimal intensity parameter, and then obtains the liquefaction displacement hazard curve; Annual average exceedance rate density of optimal vector intensity parameters In the formula, and are the median and standard deviation of the intensity parameter IM1 calculated by the earthquake motion prediction equation at a given magnitude m and focal distance r; and are the mean and standard deviation of IM2 given z1, m and r respectively; The annual average exceedance rate density of intensity parameters IM1 and IM2 is convolved with the conditional probability of liquefaction lateral displacement LD when IM1 = z1 and IM2 = z2 to obtain the annual average exceedance rate of liquefaction lateral displacement LD: Where, P[LD>x|IM1=z1,IM2=z2] represents the probability that the lateral displacement is greater than x when IM1=z1 and IM2=z2; The control unit is connected to the long-term data acquisition unit, the site model establishment unit, the monitoring and recording unit, the identification unit, the prediction model construction unit, and the risk analysis unit to control their operations.

8. The device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake according to claim 7 is characterized in that: Also includes: The input display unit is communicatively connected with the long-term data acquisition unit, the site model establishment unit, the monitoring and recording unit, the identification unit, the prediction model construction unit, the risk analysis unit, and the control unit, and displays corresponding information according to the operation instructions input by the user.

9. The device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake according to claim 8 is characterized by: in, The input display unit can display the long-term seismic data selected by the long-term data acquisition unit according to the corresponding operation instructions, display the micro-tilt site model established by the site model establishment unit, display the data information monitored and recorded by the monitoring and recording unit, display the judgment of the identification unit and the identified optimal vector seismic intensity parameters, display the liquefaction lateral displacement prediction model established by the prediction model construction unit, and display the annual average exceedance rate density solved by the risk analysis unit. The annual average exceedance rate of liquefaction lateral displacement LD is displayed.

10. The device for analyzing the probability risk of liquefaction lateral displacement of a site induced by a long-lasting earthquake according to claim 7, characterized in that: in, The liquefaction lateral displacement prediction model in the prediction model construction section is: ln(LD)=a1×ln(IM j )+a2×|ln(IM j )] 2 +a3×ln(IM i )+a4×ln(Dr)+a5×ln(H L )+a6×ln(S)+a7×[ln(S)] 2 +a8 Where LD is the liquefaction lateral displacement, Dr is the relative density of the liquefiable layer, and H L is the thickness of the liquefiable layer, S is the site inclination, and a1~a8 are constants to be solved.

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