Test equipments were designed and manufactured for producing moisture migration in unsaturated loess under freezing effect. The results showed that both the amount of freezing-thawing cycles and initial water content of soil samples affect the process of moisture migration. As the freezing front advanced in the sample, the water content in the unfrozen part significantly reduced and the water content in the freezing part significantly increased, with the maximum water content at the freezing front. Comparing to the moisture migration in the unfrozen part, the moisture migration to the freezing front in the freezing part was relatively slow. For soil samples with higher initial water content, the increment of water content at the freezing front was higher and sometimes ice could be formed. During a certain amount of freezing-thawing cycles, the water content at the freezing front kept increasing. However, as the amount of freezing-thawing cycles continued increasing, the freezing front started to move to the part with negative temperature and the maximum water content appears at the end with the lowest temperature.

The thickness of the overlying soil layer has a certain influence on the blasting vibration response of deep rock mass. The vibration wave velocity of the overlying soil layer during the construction of deep blasting is measured in this paper. Based on the measured data, parameters k and α of the Sadowski equation are used to characterize the influence of the comprehensive geological conditions of the site on the vibration wave propagation. The model of blasting vibration velocity of deep rock mass is established according to the existing blasting theory, and the calculation accuracy of the model is verified according to the field blasting parameters. The new model is used to simulate different overlying soil thicknesses, and the safe allowable distance under different soil thicknesses is calculated. The calculated results show that with the increase of the thickness of the overlying soil layer, the blasting vibration velocity decreases and the attenuation velocity decreases gradually. The research results reveal the reduction effect of overlying soil thickness on blasting vibration to some extent. In the area with overlying soil layer, the safe allowable distance of blasting vibration safety can be appropriately reduced to increase the land utilization rate, which has important reference value for the blasting design and safety prediction of deep rock mass.

It mainly reviewed the current research status of the bearing characteristic of rock-socketed piles. From reading all kinds of calculation model in different code, it pointed out the disadvantages. It concluded the present work on the two main factors which influence the bearing capacity of rock-socketed pile most. Based on this work, it figures out the deficiencies of the research presently and prospects the future research. In the end, it suggests that the bearing behavior and failure mechanism of rock-socketed piles with thick sediments remains need to be further discussed.

This paper investigates the skin friction transfer characteristics of the rock-socketed section of a rock-socketed pile resting on thick sediment by conducting in situ core-drilling tests and static loading tests. Test results show that when using the impact hole-forming method in weakly cemented soil, a layer of sediment is deposited at the pile bottom. Due to the existence of sediment, when the load reaches a certain value, sudden and large subsidence is observed. This indicates that the end resistance does not contribute to the bearing capacity. Thus, it is not appropriate to consider both end resistance and side resistance in the existing design method of a rock-socketed pile. The bearing capacity of a single rock-socketed pile should be determined according to the side resistance of the soil layer and rock-socketed section only. Numerical analysis is performed to determine the deformation and load-carrying capacity of the pile and the distribution of friction on the sides of the rock-socketed segment. Under a given applied load, small settlement is observed when socketed thickness and rock strength are relatively large. The distribution of side friction of the socketed segment along the vertical direction shows a double-peak saddle shape. When the socketed thickness and rock strength are relatively smaller, the lower peak is higher than the upper peak, and conversely, when the socketed thickness and rock strength are relatively larger, the lower peak is smaller than the upper peak. For a given applied load on the pile top, smaller socketed thickness results in larger settlement and side friction. Due to the thick layer of sediment, the axial force of the rock-socketed segment of the pile gradually decreases along the vertical direction from the applied load on the pile top to zero at the bottom. According to the mechanical properties at different shear stages, a function is derived for the complete constitutive model for a pile-rock interface. Analytical solutions for the friction of a single pile are obtained under the conditions of failure and elasticity deformation of the surrounding rock. Its load transfer equation is derived as well. Accordingly, an equation is proposed for calculating the bearing capacity of rock-socketed piles resting on sediment at the bottom.