In the reliability analysis of the landslide-stabilizing piles system (LSP), the most commonly used uncertainty models of geotechnical parameters mainly include the homogeneity model (HM) and unconditional random field (UCRF). However, neither of these models considers the existence of borehole data, which may lead to overestimation of the degree of site uncertainty. Based on borehole data in situ, the conditional random field (CRF) of the shear strength of the sliding surface was established through random field theory and the Kriging estimation method. By combining the limit equilibrium method (LEM) and Monte Carlo simulation (MCS), a novel procedure was introduced that can calculate the stability coefficient and design thrust of pile stabilization at the same time. By considering multiple failure modes comprehensively, a calculation flowchart for the failure probability of the LSP was proposed. The spatial layout parameters of pile stabilization, including the pile location, pile spacing, and pile length, significantly impact the calculation results. Compared with using HM and UCRF, the failure probability of the LSP may be lower when using CRF. Based on the allowable failure probability, feasible design solutions were provided. Further comparisons were made on the number of feasible solutions under these three uncertainty models. The research results in this paper might provide some assistance for the optimization of pile stabilization.

In rock engineering, the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations, embedded rock piles and rock bolts. In this study, 30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface. The bonding interface contains two states, i.e., the bonding interface is not sheared, termed as s(e) (symbolic meaning see Table 1); the bonding interface is sheared with rupture surface, termed as s(i). The effects of lithology, Joints structure, rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated. The test results show that the shear strength of the bonding interface (s(e) & s(i)) of columnar jointed basalt with concrete is greater than that of the bonding interface (s(e) & s(i)) of non-columnar jointed one with the same rock type grade. When the rock type grade is III2, f(col) is 1.22 times higher than f(ncol) and c(col) is 1.13 times greater than c(ncol). The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies. The cohesion of the bonding interface (s(i)) of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface (s(i)) of breccia lava with concrete under the same rock type grade condition. Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface (s(e) & s(i)). c(nol) increases by 33% when the grade of rock type rises from III1 to II1. the rock type grade has a greater effect on bonding interface (s(i)) cohesion than the coefficient of friction. When the rock type grade is reduced from III2 to III1, f(ncol)(') increases by 2% and c(ncol)(') improves by 44%. The shear strength of the non-columnar jointed basalt-concrete bonding interface (s(e) & s(i)) increases with the increase of the compressive strength of concrete. When concrete compressive strength rises from 22.2 to 27.6 MPa, the cohesion increases by 94%.

Columnar jointed basalt (CJB) widely distributes in the dam site of the Baihetan Hydropower Station. The columnar joint structure and fracture development of CJB have significant influence on the mechanical properties of rock mass, and the mechanical properties of CJB are of great significance to the Baihetan Hydropower Project. Therefore, in-situ direct shear tests were carried out on ten test adit at different locations in the dam site area to study the shear behavior of CJB. In this study, 21 sets of in-situ direct shear tests were conducted for rock types of type II2, type III1 and type III2, with horizontal and vertical shear planes and two different specimen sizes of CJB. Shear strength parameters of CJB were obtained by linear fitting of in-situ direct shear test results based on the Mohr-Coulomb strength criterion. The results indicate that the shear strength parameters of CJB with horizontal shear plane increase as the increase of rock type grade. The shear strength parameters of CJB show obvious anisotropy and the friction coefficient of the horizontal shear plane is greater than the vertical shear plane. The friction coefficient in the horizontal direction of the shear plane is 1.27 times that in the vertical direction of the shear plane. With the increase of rock type grade, the difference of friction coefficient becomes larger. However, the cohesion changes little whether the shear plane is horizontal or vertical. In addition, the size effect of CJB in this area is significant. The shear strength parameters of large size (100 cm x 100 cm) specimens are lower than those of regular size (50 cm x 50 cm) specimens. The reduction of cohesion is greater than that of the friction coefficient. For rock type III2, the cohesion of large-size specimens is 0.637 of the regular-size specimens. The reduction percentage of the friction coefficient for type III2 is 1.66 times that of type III1. The reduction percentage of the cohesion for type III2 is 1.27 times that of type III1. The size effect decreases with the increase of rock type grade. The research results of this study can provide an important basis for the selection of rock mechanics parameters in the dam site area of Baihetan Hydropower Station and the stability analysis of the dam foundation and rocky slopes.

In this work, we obtain necessary and sufficient conditions for the oscillation of all solutions of delay fractional differential equation of the form (Formula Presented) where (Formula Presented) odd integer odd integer. Furthermore, we supplement the theoretical aspects with numerical simulations and illustrations. © 2023, IAENG International Journal of Applied Mathematics. All Rights Reserved.

三峡库区广泛分布侏罗系红砂岩，在水库运行期间红砂岩的渗流-应力耦合特性关乎库区内多数滑坡和岩质边坡的稳定性。借助岩石多场耦合三轴试验系统，对三峡库区侏罗系红砂岩开展了不同围压、不同渗透压下的三轴压缩试验，系统研究了红砂岩的三轴压缩力学特性和渗透率演化特征。研究结果表明：（1）红砂岩的峰前应力-应变曲线可分为孔隙压密阶段、弹性变形阶段、微裂隙稳定发展阶段和非稳定发展阶段。红砂岩的力学参数与渗透压的关系呈负相关，与围压呈正相关。（2）随着围压升高，红砂岩的破坏模式由张拉破坏过渡到剪切破坏。（3）不同渗透压下，渗透率曲线呈平稳发展→缓慢上升→快速上升3阶段演化规律；不同围压下，渗透率曲线先降低后升高。（4）从能量角度分析了渗透压和围压对岩石的作用，验证了渗流对岩石的劣化效应以及围压对裂纹发展的抑制作用。本试验对鲜有报道的侏罗系红砂岩的强度、变形和渗透特性做了系统的研究，对渗流-应力耦合课题有补充意义。其工况根据三峡库区边坡岩体的应力水平来确定，试验结果对分析库区边坡稳定性具有指导意义。

Many large landslides may have multi-sliding zones that are simultaneously active due to the influence of engineering geological and hydrogeological conditions. Here, a simplified multi-sliding zone landslide model is developed to reproduce the deformation behavior and evolution process of landslides. A multi-sensor monitoring system is implemented to record the surface deformation, subsurface deformation, and soil pressure during the test. The flexible inclinometer sensor technique is utilized for subsurface relative deformation monitoring in the model test. A uniform thrust loading is applied on the trailing edge of the model. The results show that the displacement evolution reflects four stages, namely, initial, constant, accelerative, and failure stages, and the evolutionary process of each landslide at different depths is different. The variation trends of soil pressure are similar to those of subsurface displacement, which can be classified into four analogous stages. When landslide failure occurs, the soil pressure drops suddenly. The variation of soil pressure could reflect the energy state of the multi-sliding zone landslide. The correlation coefficients between the soil pressure and the subsurface relative displacement are different among the multi-sliding zones. During the test, the soil pressure of the multi-sliding zones landslide presents a complicated multistage trapezoidal distribution, and the multi-sliding zones have the greater soil pressures. Under the action of thrust loading and gravity, translational sliding with multi-sliding zones occurred, and local shear sliding occurs at the front of the landslide. This research provides improved insight into the evolutionary process of the multi-sliding zone landslide.

水库蓄水后,滑坡体碎石土经受长时期的浸泡,力学性质发生改变,从而影响滑坡整体稳定性。为探究浸泡对碎石土力学性质的影响规律,本次研究选取坡体后缘未经受长期浸泡作用的碎石土进行大型直剪试验,分析了不同浸泡天数下碎石土的剪切力学性质。试验结果表明:浸泡40d后,碎石土黏聚力下降幅度达39%,内摩擦角下降幅为8.3%;碎石土黏聚力在浸泡前期快速下降,下降速率随浸泡天数增加而降低,浸泡20d后,黏聚力基本达到稳定。为探究碎石土抗剪强度降低的原因和机理,对粉质黏土（碎石土细粒成分）进行了三轴剪切试验、激光粒度分析及浸出液阳离子分析等试验,揭示了碎石土抗剪强度的衰减机理为:浸泡作用下,碎石土中的粉质黏土发生矿物溶解、离子交换与吸附作用,土体中大颗粒细化,胶结作用减弱,进而导致碎石土整体抗剪强度降低。本研究对库区碎石土滑坡评价与治理具有一定的指导意义。

水库蓄水后，滑坡体碎石土经受长时期的浸泡，力学性质发生改变，从而影响滑坡整体稳定性。为探究浸泡对碎石土力学性质的影响规律，选取三峡库区马家沟滑坡后缘未经受长期浸泡作用的碎石土进行大型直剪试验，分析了不同浸泡天数下碎石土的剪切力学性质。试验结果表明：浸泡40 d后，碎石土黏聚力下降幅度达39%,内摩擦角下降幅度为8.3%;碎石土黏聚力在浸泡前期快速下降，下降速率随浸泡天数增加而降低，浸泡20 d后，黏聚力基本达到稳定。为探究碎石土抗剪强度降低的原因和机理，对粉质黏土（碎石土细粒成分）进行了三轴剪切试验、激光粒度分析及浸出液阳离子分析等试验，揭示了碎石土抗剪强度的衰减机理为：浸泡作用下，碎石土中的粉质黏土发生矿物溶解、离子交换与吸附作用，土体中大颗粒细化，胶结作用减弱，进而导致碎石土整体抗剪强度降低。研究结果对库区碎石土滑坡评价与治理具有一定的指导意义。

Soil–rock mixtures are commonly encountered in the construction of bored piles. Conventional bentonite support fluids have disadvantages, such as more significant environmental impacts, more complex mixing, bigger site footprint, weaker foundation performance, and overall low economies. The present study conducted a comprehensive investigation of partially hydrolyzed polyacrylamide (PHPA) polymer fluids, an alternative to bentonite ones, to drill into a soil-limestone mixture. The fluid flow pattern, aging behavior, and the influence of finer silty clay on polymer fluid were explored. The test results showed that polymer fluids were reasonably well fitted to the power-law model and were a good alternative to the conventional bentonite ones. In terms of their aging behavior, the remaining active viscosity of the polymer was at least 70% after a prolonged aging time of up to 30 days, showing the effective on-site use of polymer fluids. The mixing of silty clay significantly reduced the apparent viscosity of polymer fluids, with 10% silty clay causing a viscosity reduction of 76%, indicating the importance of fluid control in drilling these materials. A polymer formula, water + 0.08%PHPA + 0.1~0.5%Na2 CO3, was proposed and was verified by drilling into a soil–limestone mixture. The polymer fluids led to small radial displacements around the boreholes with a high drilling quality. This work would be helpful for consultants and contractors designing and constructing bored piles in soil and rock mixtures utilizing polymer fluids. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.