Physical model experiment on the influence of water depth on the underwater pipeline surface impacted by landslide surge

A physical model experiment of flume block landslide was used to study the influence of landslide surge impact on underwater pipeline surface under different water depths. The influence of surge impact pressure on pipelines with different water depths and the impact pressure of surge at different angles of underwater pipelines wall were analyzed. And the relationship between the maximum impact pressure of underwater pipelines and the depth of water was obtained. The results indicated that with the decrease of the water depths, the maximum impact pressure at the wall of the underwater pipeline increases approximately linearly, and the slider is easier to form higher first wave height. The maximum impact pressure of the upper surface of the pipeline wall is greater than that of the lower surface of the pipeline wall under the same working conditions. It is also found that the smaller the depth of water, the larger the maximum pressure and average pressure at the measuring point would be and the greater the pressure fluctuation becomes when slider volume and landslide water inlet angle and speed remain the same.

Subsidence Characteristics Study on the Highway and Substrata Overlying Acute Inclined Shallow Mined-out Area Under Different Mining Heights and Mining Angles

Based on an actual highway project traversing an acute inclined shallow mined-out area in Urumqi, China, a scale physical model experiment and numerical simulation method were adopted to study the stability and settlement mechanism of the highway subgrade and substrata overlying an acute inclined mined-out area under different mining heights and mining angles. Plastic pneumatic capsules with different shapes were embedded in similar strata made from clay, fine sand, and Vaseline to simulate the mined-out cavity. The capsule was removed to simulate the process of mining, and five cases with different mining heights and angles were studied. According to similarity theory, a physical model was established with a geometric similarity coefficient of 50 of the actual prototype, whereas the numerical model adopted the full-scale value. The physical model experiments and numerical simulations show that the settlement of the subgrade and substrata overlying the mined-out area is directly proportional to the mining height but inversely proportional to the mining angle. According to the settlement contour obtained by numerical simulations, which were in accordance with the physical model experiment results, two parameters, the free slip volume and the free surface, were defined to assess the stability of the subgrade and substrata overlying the mined-out area. The free slip volume and free surface calculation results demonstrate a strong relationship between the settlement and free slip volume and free surface. Therefore, the values of free slip volume and free surface could be reliable reference parameters to evaluate the stability of the subgrade and substrata overlying mined-out areas.

Analysis of Slope Stability and Disaster Law under Heavy Rainfall

Based on this, the slope stability and disaster law under the condition of heavy rainfall are studied. With the slope of Shangge Village as the background, the slope stability under the condition of heavy rainfall is deeply studied through theoretical analysis, laboratory physical model experiment, and numerical simulation. Results showed that due to the heavy rainfall within 2 h, the deformation of the slope is not obvious in the rain 2 h~7 h period, first of all in the position of slope toe of slope stress raiser; As the rainfall continued, the infiltration of rainwater led to weakening of the rock mass strength, and the cracks in the slope fracture zone further expanded and extended to the top of the slope. After 7 hours of rainfall, the slope formed a sliding surface. The physical model experiment and the numerical simulation results are in good agreement, which can provide the basis for slope reinforcement under heavy rainfall conditions and have important scientific significance and social value for the reasonable site selection of housing construction, transportation network, and disaster prevention and mitigation in coastal areas.