Dynamic Response Of Slope Research Articles

Dynamic response of high and thin rock slope under blasting vibration: a case study

The topography of a thin double-sided rock slope differs greatly from that of a regularly studied single-sided rock slope, which leads to difficulties in investigating the dynamic response of the thin double-sided rock slope. Through a case study, this paper provides a specific prospect on the dynamic response of the high and thin rock slope under blasting vibration. The high and thin rock slope belonging to Chiwan Mountain was selected as the typical case slope. Field monitoring programs for blasting vibration on the case slope were carried out using vibration monitoring systems. The amplitude, frequency, and energy characteristics of the recorded blasting vibration were then concretely identified and examined. The monitoring results were further used to validate the dynamic finite element model developed to explore the effects of blasting vibration frequency and amplitude on the dynamic response of the slope. The dynamic finite element model of the case slope subjected to blasting vibration was established using the software LS-DYNA. According to the monitoring and numerical results, the dynamic response mechanism of the high and thin rock slope under blasting vibration was discussed. The results indicate that the elevation amplification effect of blasting vibration exists on the southern slope from a certain elevation, and the dominant frequencies generally decay with the distance from the blasting source but remain largely the same within a specific elevation range. The blasting vibration frequencies have considerable influence on both the values and distributions of peak particle velocities on the slope while the blasting vibration amplitudes have an impact only on the values of peak particle velocities. The dynamic response of the case slope under blasting vibration results from the joint effects of blasting seismic wave propagation and structural resonance. The research findings may pave an effective way to clearly understand the dynamic response of similar high and thin rock slopes under blasting vibration.

Dynamic Response Law and Failure Mechanism of Slope with Weak Interlayer under Combined Action of Reservoir Water and Seismic Force

The southwestern region of China is close to the Eurasian earthquake zone. Many engineering areas in southwestern China are affected by earthquakes and are close to the epicenter of earthquakes that occur in this region. During earthquakes, slopes with weak interlayers are more likely to cause large-scale landslides. In response to the low stability of slopes with weak interlayers in reservoir dam areas, the dynamic response law and failure mechanism of weak interlayered slopes under the combined action of reservoir water and seismic forces were studied through shaking table model tests and finite element numerical simulation software. The height of the water level and the size of the seismic waves were changed during these tests. The research results indicate that seismic waves are influenced by weak interlayers and are repeatedly superimposed between the weak interlayers and the slope surface, resulting in an acceleration amplification effect that increases by approximately 1.8 times compared to homogeneous slopes. Vertical earthquakes have a significant impact on the dynamic response of slopes, and their peak acceleration amplification coefficient can reach 0.83 times the horizontal peak acceleration. The stability of weak interlayers during earthquakes is the worst within the range of the direct action of reservoir water. The failure mode of a slope is as follows: earthquake action causes cracking in the upper part of the slope, and as the earthquake increases in intensity, and the infiltration of reservoir water intensifies, the cracks expand. The soft and muddy interlayer in the front section of the slope forms a sliding surface, and ultimately, the sliding failure forms an accumulation body at the foot of the slope. In reservoir dam areas, the stability of a slope is closely related to the engineering safety of the reservoir dam. Therefore, when a strong earthquake and the water level in a reservoir jointly affect a weak-interlayer slope, the slope is in the stage of plastic deformation and instability. The stability of the slope may be overestimated, and the slope is likely vulnerable to sliding instability, which needs to be monitored and treated.

Research on Dynamic Response of Slopes With Weak Interlayers Under Mining Blasting Vibration

As blasting technology starts to be used in a wide range of areas, blast loading has led to an increasing number of geological disasters such as slope deformation, collapses, and soil slippage. Slopes with weak interlayers are more likely to be deformed and damaged under the influence of blast loading. It is of great importance to study the evolution for the deformation of slopes with weak interlayers during blasting excavation. This study constructed a slope model with a weak interlayer to investigate the influence of different factors of blasting, including explosive charge, blast radius, blast origin, and multi-hole blasting, on the internal dynamic response. The deformation mechanism of slopes with weak interlayers under the influence of blast loading was analyzed. Test results show that each layer of the model had a different displacement response (uncoordinated dynamic response) to blasting with various factors. Explosive energy and the pattern of dynamic response of each layer varied depending on different settings of blasting factors such as explosive charge, blast radius, blast origin, and detonation initiation method. When the explosive energy produced under the influence of various factors was small, the change in the uncoordinated dynamic response between layers was significant, and the change gradually became less significant as the explosive energy increased. Therefore, this study has proposed the concept of critical explosive energy, and it is speculated that when the explosive energy produced with various factors is less than critical explosive energy, the dynamic response is mainly affected by the internal structure of the slope (property difference induced geologic layers). In other words, the uncoordinated motion of material’s particles in each layer is caused by different limitations and the degree of movement of the particles, which leads to the uncoordinated dynamic response and uncoordinated deformation of each layer. If the explosive energy is greater than the critical value, the dynamic response of each layer is mainly affected by the explosive energy. The differences in the internal structure of the slope are negligible, and the incoordination of dynamic responses between layers gradually weakens and tends to synchronize.

Study on dynamic response of slope under near-fault pulse-like ground motion

Compared with far-field ground motion, the most significant feature of near-fault pulse-like ground motion is the long-period, large-scale velocity pulse. This paper proves through statistical analysis that near-fault pulse-like ground motion is an important cause of slope damage and landslide. And use numerical simulation software FLAC3D to establish a homogeneous rock slope model, select near-fault ground motions with velocity pulses and non-pulse near-fault ground motions, and use an improved energy method to identify and extract the selected near-fault ground motions. The dynamic response of the slope under the action of near-fault ground motions with and without velocity pulses is comparatively studied, and the dynamic response law of the slope under the original records, pulse records, and residual records of pulse-like ground motions is explored. The research results show that the near-fault ground motions with velocity pulses can cause a greater dynamic response than ground motions without velocity pulses. There is an elevation magnification effect in the PGA distribution of the slope horizontally. The shorter-duration pulse record can cause a larger dynamic response, and the PGA magnification factor under the effect of the residual record is smaller than the original record. The velocity pulse strengthens the earthquake damage to the slope, and the slope produces a stronger dynamic response.

Dynamic response of rock slope with anti-dip weak interlayer and its influencing factors under seismic actions

The load features of ground motion are mainly reflected by three factors: amplitude, frequency, and duration. The combination of these factors determines the response of rock-soil mass and the structure safety under seismic load. By finite element method, this paper analyzes the influence of the three factors of ground motion on the dynamic response of a slope. The analysis shows that the slope displacement increased with the elevation from the bottom. The anti-dip fault puts the slope in an unfavorable deformation state. Due to the large residual deformation in the fault zone, a large displacement occurred on the slope top. It was also learned that the adjustment of amplitude only leads to proportional growth in the absolute value of the acceleration of the slope. Under the same conditions, the dynamic responses in different parts of the target slope are not greatly affected by the changing amplitude, but depend more on the material and spectral features of the rock-soil mass. The research results provide a reference for the evaluation and prediction of slope seismic stability and the evolution of slope damage under earthquakes with different frequencies, amplitudes, and durations.

Investigation of the seismic response characteristics of a rock mass slope containing weak structural planes under seismic excitation based on multi-domain coupling analysis

Because of the complexity of interactions between seismic waves and rock masses, the dynamic response of slopes has typical multi-domain characteristics. To fully consider the multi-domain characteristics of ground motion, the dynamic response of a rock slope containing weak structural planes was systematically investigated in the time domain, frequency domain, and time-frequency domain. Two-dimensional dynamic analyses were carried out on two numerical models, including the homogeneous slope- and slope-containing structural planes. The results show that slopes containing structural planes have dynamic topographic and geological amplification effects. Based on the frequency-domain analysis, the relationship between the frequency of waves and the dynamic response of slopes was further studied. The geological structure influences the high-frequency components of waves in slopes containing structural planes. The analyses of the marginal spectrum show that seismic energy is mainly concentrated in the frequency band of waves (7–10 Hz). In addition, the seismic failure mechanism of slopes containing structural planes was explored. Structural planes have an important effect on the seismic failure mode of slopes containing structural planes. Multi-domain coupling analysis can reveal the seismic response characteristics of slopes more comprehensively and provide a reference for the seismic design of rock slopes.

Failure Mechanism of Rock Slopes under Different Seismic Excitation

In earthquake‐prone areas, special attention should be paid to the study of the seismic stability of rock slope. Particularly, it becomes much more complicated for the rock slopes with weak structural surfaces. In this study, numerical simulation and the shaking table test are carried out to analyze the influence of seismic excitation and structural surface in different directions on dynamic response of rock slope. Huaping slope with bedding structural surfaces and Lijiang slope with discontinuous structural surfaces besides Jinsha River in Yunnan Province are taken as research objects. The results of numerical simulation and the model test both show that discontinuous structure surface has influence on the propagation characteristics of seismic wavefield. For Huaping slope, the seismic wavefield responses repeatedly between the bedding structural surface and slope surface lead to the increase of the amplification effect. The maximum value of seismic acceleration appears on the empty surface where terrain changes. Horizontal motion plays a leading role in slope failure, and the amplification coefficient of horizontal seismic acceleration is about twice that of vertical seismic acceleration. The failure mode is integral sliding along the bedding structural surface. For Lijiang slope, seismic acceleration field affected by complex structural surface is superimposed repeatedly in local area. The maximum value of seismic acceleration appears in the local area near slope surface. And the dynamic response of slope is controlled by vertical and horizontal motion together. Under the seismic excitation with an intense of 0.336 g in X direction and Z direction, the amplification coefficients of seismic acceleration of Lijiang slope are 3.23 and 3.18, respectively. The vertical motion leads to the cracking of the weak structural surface. Then, Lijiang slope shows the toppling failure mode under the action of horizontal motion.

Numerical study on seismic response of a rock slope with discontinuities based on the time-frequency joint analysis method

To clarify the seismic response of rock slopes, a time-frequency joint analysis method with the combined use of time, frequency and time-frequency domain analysis is proposed. The dynamic response of a rock slope with discontinuous structural planes was investigated using the finite element method (FEM). A two-dimensional model incorporating finite element meshes with infinite element boundaries for the slope was used in the FEM dynamic analyses. The numerical results show that the elevation, structural plane and direction of wave propagation have an impact on the slope amplification effect. The peak ground acceleration (PGA) under horizontal seismic excitation is approximately 1.2–1.3 times that under vertical seismic excitation. In addition, the first three natural frequencies of the slope can be obtained from the Fourier spectrum and modal analysis. The low-frequency components (<20 Hz) and high-frequency components (>20 Hz) mainly induce the overall and local deformation of the surface slope, respectively. Moreover, the dynamic response of the slope was further investigated by analysing the seismic Hilbert energy. The seismic Hilbert energy in the Hilbert energy spectrum and marginal spectrum is mainly distributed in the low-frequency and high-frequency regions, respectively. The applicability of the Hilbert energy spectrum and marginal spectrum to analyse the dynamic deformation characteristics of the slope is identified. Moreover, the relationship between the local dynamic deformation response of the slope and the occurrence of a landslide was discussed. The dynamic failure mechanism of the slope was clarified according to the frequency-domain and time-frequency domain analysis.

Effects of Moisture Content on the Dynamic Response and Failure Mode of Unsaturated Soil Slope Subjected to Seismic Load

Understanding the relationship between the moisture content of unsaturated soil and the instability and dynamic response of slope under the action of seismic load can bring convenience to the field of slope safety assessment. The effect of moisture content of the unsaturated soil on the failure mode and dynamic response of slope under seismic loading was investigated using shaking table tests. In this regard, three different moisture contents of 5%, 8.1%, and 12.5% were considered. The experimental results show that the amplification factor of acceleration (AFA) on the slope surface increases with the increase in both relative elevation and excitation amplitude of acceleration (EAA). As the moisture content of unsaturated soil increases, AFA tends to decrease. An empirical correlation describing the relationship among AFA, relative elevation, dimensionless EAA, and moisture content of unsaturated soil was proposed. The excitation frequency of acceleration (EFA) has a significant impact on the AFA at the middle and upper parts of the slope. The deformation of slope surface is able to reflect the failure mode of slope, which can be used in slope monitoring work. The slope with different moisture contents of unsaturated soil has different instability modes. With the increase in soil moisture content, the slope needs more energy to reach the unstable state under seismic loading. There are three typical regions of principal stress field in the slope exposed to seismic loading, which control the evolution of initial slip plane inside the slope.

Dynamic Failure Mode and Dynamic Response of High Slope Using Shaking Table Test

A shaking table test was performed to study the dynamic response and failure modes of high slope. Test results show that PGA amplification coefficients increased with increasing elevation and the PGA amplification coefficient of the concave slope was slightly larger than that of the convex slope. The slope type affected the dynamic response of the slope. The elevation amplification effect of the concave slope under seismic load was more significant than that of the convex slope; thus, the concave slope was more unstable than the convex slope. Additionally, the PGA amplification coefficient measured on the slope surface was always larger than that inside the slope, and the data show an increasing trend with the broken line. The dynamic amplification effect of the high slope was closely related to the natural frequency of the slope. Within a certain range, the higher the frequency, the more significant the amplification effect. The dynamic failure process of concave and convex slopes was studied through tests. Findings indicate that the dynamic failure modes of the concave slope are characterized by shoulder collapse, formation of the sliding surface, and integral sliding above the slope line. Dynamic failure modes of the convex slope are mainly slips in the soil layer and collapse of the slope near the slope line.

A Monte Carlo simulation technique for assessment of earthquake-induced displacement of slopes

The dynamic response of slopes against earthquake is commonly characterized by the earthquake-induced displacement of slope (EIDS). The EIDS value is a function of several variables such as the material properties, slope geometry, and earthquake acceleration. This work is aimed at the prediction of EIDS using the Monte Carlo simulation method (MCSM). Hence, the parameters height, unit specific weight, cohesion, friction angle, vibration duration, and maximum horizontal acceleration are used to predict the EIDS values. To do this, a multiple non-linear regression relationship is first derived between EIDS and the independent variables. Then MCSM is performed based on the developed regression equation. The results obtained demonstrate that the stochastic approach used is able to successfully reproduce the EIDS values and calculate the confidence intervals. The average of the measured and simulated values for EIDS was 4.34 cm and 4.48 cm, respectively. Eventually, the results of a performed correlation sensitivity analysis revealed that the maximum horizontal acceleration had the greatest impact on EIDS.

Study on Seismic Response Characteristics of Hinge-Type Slope

Considering the influence of dynamic interaction between soil and structure, a finite element analysis model of nonlinear dynamic interaction of hinge type slope is established. Then, numerical simulation towards its seismic response has been carried out. Analysis on stress, acceleration and response characteristics of relative horizontal displacement under different seismic oscillation are conducted. Whose results represent that when at the same intensity and spectrum of earthquake motion, the maximum dynamic stress in the middle and upper part of slope is larger while the acceleration and horizontal displacement of the top and bottom is higher. If under earthquake motion with the same intensity and different spectrum, the dynamic response of slope under Loma Prieta wave is larger than that under Kobe wave. Considering the seismic response characteristics of slope, its top and bottom are weak areas. Therefore, attention should be paid to these places in seismic design, same emphasis should also be given to the middle and middle-upper part.

Laws of Influence upon Dynamic Response of High Rock Slope by Seismic Wave Frequency

On the basis of seismic wave recorded by Wolong Measuring Station in Wenchuan Earthquake occurred on May 12, 2008, and taking a high rock slope (about 1397m in height) at the bank of Zipingpu Reservoir as the specific example, analyses have been made, with Plaxis dynamical simulation analysis program, on characteristics of influence upon acceleration time history, shear strain distribution, principal stresses distribution and stability of high rock slope by original seismic wave, and seismic wave with frequency expanded by 1.5, 2 and 3 times, respectively. Results of the analyses demonstrate that dynamic response characteristics of the slope top are notably influenced by multiplication factor of seismic wave frequency. As far as the real slope in this article is concerned, it generally presents a gradual decrease of PGA of the top of high rock slope, reduction of slope body shear strain and a corresponding drop of dynamic response of slope body as a whole, with the increase of seismic wave frequency.

Research the Excavation Angle Affect on Seismic Dynamic Response of Slope

Based on the concentrated deformation and destruction characteristics of excavation damage slopes in Wenchuan earthquake，as granite the media of excavation damage slope for the finite element model. In 45° slope as the natural slope，the excavation damage effect and seismic dynamic response of different excavation angle have been studied under the excavation high is certain condition, it’s include natural slopes, excavation angle 56°, 72° and 90°. Analysis shows that excavation damage not only themselves destroyed the stress balance of slopes, but also impact on the seismic dynamic response of slopes, and the seismic dynamic stress, displacement and acceleration increased with the increase of slope angle. It’s not conducive to the stability of slope and the results coincides with the investigation conclusion that Wenchuan earthquake mountain disaster outbreak in the terrain mutation site. And the analysis also shows that slow excavation angle is an important measure to improve the seismic performance of the slope.

Earthquake resistant design of cohesive earth slopes

As many major slope failures have occurred during medium and strong earthquakes, the assessment of the seismic stability of slopes in earthquake-prone areas is of great concern to engineers. Prior to 1964, little attention was given to the development of rational aseismic design methods for earth slopes. Most design methods were based on a static analysis used in conjunction with an arbitrarily selected lateral force acting on the slope with soil strengths determined by conventional laboratory tests. However, the catastrophic slope failures which occurred during the Alaskan earthquake of 1964, resulted in a considerable reappraisal of such static design methods. In recent years significant progress has been made in developing new methods of laboratory testing to determine dynamic soil properties, improved techniques of analysing the dynamic response of slopes and embankments to earthquakes, and new concepts of aseismic design methods for earth slopes. Although research has yet to provide all the answers, the current state of knowledge at least provides an improved guide to engineering judgement in the assessment of the stability of earth slopes during earthquakes.