The instability of the bank slope of the reservoir will cause great loss to the life and property of the people in the reservoir area. The landslide of the reservoir not only occurs in the period of water level plummeting, but also occurs in the period of water level rising. In this paper, the mechanism of slope landslide in the rising stage of water level was studied from the perspective of soil disintegration in water. A series of tests on the disintegration of prisms and cylinders with the same volume and different bottom side lengths (diameter) were carried out. The results show that the specific surface area of the same volume sample was different, and the disintegration behavior was different. The larger the specific surface area of the same shape sample was, the faster the disintegration speed was. The deeper the water depth was, the shorter the disintegration time was under the same initial conditions. It shows that when the water level of the reservoir rose, the deeper the water depth was, the greater the pore osmotic pressure was, and the more the soil mass of the slope collapsed. This led to the reduction of the pressure on the lower part of the slope, the decrease of the antisliding force of the soil, and the failure of the slope.

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The moisture content of municipal sludge is relatively high, which increases the cost of sludge transportation and treatment. To reduce the volume of the sludge, sludge dewatering is needed. This paper proposes the theory of sludge dewatering and facilitates efficient and economical technology of sludge dewatering. Sludge dewatering tests were carried out by using homemade rapid sludge dewatering devices. There were two groups of tests with single- and double-drainage conditions, and all test runs were loaded with a negative vacuum pressure at the bottom. During the experiments, the vacuum degree and the pore water pressure in the sludge were monitored in real time. After the experiments, the data were compared and analyzed. At the initial stage, the sludge dewatering extent and the sludge dewatering velocity for double-drainage conditions were much higher than those for single-drainage conditions. The vacuum occurring for single-drainage conditions lagged behind that for double-drainage conditions in the sludge. The value of vacuum degree for single-drainage conditions was lower than that for double-drainage conditions, and the vacuum attenuation for single-drainage conditions was considerable. The excess pore water pressure for double-drainage conditions dissipated faster than that for single-drainage conditions in the sludge. The pore water pressure for single-drainage conditions at the top and middle of the sludge layer first increased and then decreased in the early loading stage, resembling the Mandel effect. Overall, with a vacuum negative pressure load at the bottom, the sludge dewatering efficiency for double-drainage conditions was much higher than that for single-drainage conditions. This study provides an experimental and theoretical basis for engineering applications in the sludge treatment industry.

Many scholars have used crop straw to reinforce soft soil foundation and studied its reinforcement effect and mechanism. However, the crop straw will degrade in the soil for a long time, which reduces the tensile strength of the straw and weakens the shear resistance of the reinforced soil. In order to study the degradation law of rice straw rope and its influence on tensile properties, the straw rope was immersed in water for different time, and then taken out, the quality before and after immersion was measured and tensile test was carried out. The results showed that: the degradation of rice straw rope in water experienced two stages of rapid degradation and slow degradation, and the quality of loss in the rapid degradation stage was more; the tensile force of straw stalk rope increased slowly with the increase of tensile displacement. When immersed for 20 days, the failure mode was brittle failure, and after 40 days of immersion, the failure mode changed into ductile failure; the straw stalk rope was the main tensile force of the straw fiber, and the tensile strength peak decreased with the increase of the immersion time. The deterioration law accorded with the third-order polynomial function.

At present, the sludge production has increased sharply, and sludge treatment remains a serious problem. Rapid sludge dewatering is the key problem of sludge treatment, and the main approach for reducing the cost of the sludge treatment is to reduce the cost of sludge dewatering. In this paper, two groups of sludge dewatering tests were carried out using homemade instruments and equipment. One group was conducted without rice straw, and the other group was conducted with rice straw. The relevant mechanism was analyzed, and the results indicate that sludge dewatering with a vacuum negative pressure load of the full section at the bottom is better than mechanical sludge dewatering. The sludge dewatering effect with rice straw is better than that without rice straw. Additionally, the vacuum degree inside the sludge decreased sharply. The pore water pressure slowly dissipates during the early and late stages and quickly during the middle stage. Sludge pore water seepage does not obey Darcy’s law, and sludge dewatering is intermittent.