Slope stability calculation method for highwall mining with open-cut mines

Slope stability is a prominent problem for the efficient application and promotion of highwall mining technology, especially when mining residual coal under high and steep end-slope conditions. This study proposes the concept of target time pillar strength based on the required coal pillar service time. Creep tests were performed to measure the time-varying properties of coal shear strength parameters under different loads, and a time-varying function was established by regression. The highwall mining length is divided into three categories based on discontinuous structural plane theory, including goaf, yielding, and elastic zones, all of which are considered to have resistances against shear stress. The basal coal seam is prone to weakening owing to the weight of overlying strata, which may shift the slope failure mode from circular to sliding along the weak layer. Numerical modeling was used to study the influence of the bearing stress and target time strength on the development of the yielding zone at the coal pillar ribs. The coefficients of the three zones were determined, and the temporal and spatial evolution patterns of the shear strength parameters of the weak layer were acquired. A slope stability calculation method is proposed based on rigid body-limit equilibrium theory that can quantify the influence of highwall mining operations on slope stability, which is significant for popularizing highwall mining technology.

Stability Metric Based on Sensitivity Analysis Applied to Electrical Repowering System

Stability metrics are used to quantify a system’s ability to maintain equilibrium under disturbances. We did not identify the proposition of a stability metric using sensitivity analysis within the literature. This work proposes a system stability metric and its application to an electrical repowering system. The methodology for applying the proposed metric comprises: (i) system parameters sensitivity analysis and spider diagram construction, (ii) determining the array containing the line segments inclination angles of each spider diagram curve, and (iii) stability calculation using the array mean and maximum inclination value of a line segment. After simulating the model built for the electrical repowering system and applying the methodology, we obtain results regarding the sensitivity indices and stability values of system inputs relative to their outputs, considering the original system and with reduced parameters. Using the stability study, it was possible to determine different stability categories for the system parameters, which indicates the need for different analysis levels.

DESIGN OF RETAINING WALL USING ALTERNATIVE GABION AND RETAINING WALLS OF CANTILEVER TYPE ON SLOPE OPEN SPACE GREEN JL. KINIBALU BANJARBARU

On the construction of green open space Jl. Kinibalu Banjarbaru There is a 6 meters tall slope beneath which the river is lined up during the rainy season and makes the slope exposed by water plus the absence of load or traffic on it make the pore figures on the land is large. Therefore, for protection reason, there is a soil alignment in the construction of soil retaining walls. The planned ground retaining wall type is cantilever and gabion. The stability analysis of the ground retaining walls is done manually and with the help of the Geoslope/W 2018 software. The value of the stability of the style against the bolsters, sliding, and carrying capacity of the soil using manual calculations for cantilever type and Netlon qualifies SNI 8460:2017. And for the overall stability calculation using Geoslope/W 2018 software obtained safety factor (SF) > 1.5. From the analysis, the design of planning can be used because it is safe against the dangers of avalanche.

Remote Sensing Data Analysis for the Ecological Stability Purposes

The remote sensing offers the opportunity of miscellaneous data acquisition with various ways of their consequent analysis and application. The processed remote sensing data in the form of georeferenced orthophotoimages or orthophotomaps enable the study of the examined locality from the chosen observed feature point of view. According to periodical data acquisition, it is possible to monitor the ongoing and emerging actions in time and then prevent and predict the upcoming actions. With the increasing interest in environmental issues and nature protection, the natural environment monitoring, preservation, protection and remediation present the number one priority. From the ecological point of view, the analysis of orthophotos/orthophotomaps present the up-to-date way of ecological stability calculation and monitoring.

Unified Failure Strength Criterion for Terrace Slope Reinforcement Materials

This paper presents a study on the failure strength criterion of terrace slope reinforcement materials, such as lean cemented sand and gravel (LCSG) material, under a triaxial stress state. Cement content and confining pressure were selected as major factors to investigate their influence on the peak stress of terrace slope reinforcement materials based on experimental results and data from the literature. The mechanical properties of the LCSG samples, with cement contents of 60, 80, and 90 kg/m3, and noncemented sand and gravel materials were tested under four confining pressure levels (namely, 300, 600, 1000, and 1500 kPa). The results show that the strength of LCSG material improves as the confining pressure increases. When the confining pressure exceeds 1200 kPa, the rate of increase of the strength for LCSG material and other cemented grained materials declines generally. The material strength displays a linear increase with the growth of the cement content. When the axial load rises up to a certain value, damage will occur at the particle cemented site near the shear plane, and the resistance stress generated by the cementation shows a trend of growth first and then attenuation, and concurrently, the friction between particles increases by degrees. Based on the identified strength characteristics of LCSG material under different cement contents and confining pressures, a new strength criterion that incorporates the frictional strengths and the cementing strengths is proposed for LCSG and other similar materials. The results of this work can provide an important theoretical basis for the stability calculation of terrace slopes and LCSG dams.

Slope Stability Calculation Method of Highwall Mining with Open Cut Mines as an Example

Highwall mining machines have been used to recover retained coal at the toe of highwalls and endwalls over the past few decades. However, there has not been a universal method to evaluate the slope stability using highwall mining while maximizing the recovery rate. Based on the required service time of coal pillars, this study proposes the concept of the target time pillar strength. To obtain time-dependent parameters for the coal, time-dependent shear tests were performed on specimens from an open-cut mine in Inner Mongolia. The highwall mining length was divided into three categories based on discontinuous structural plane theory: goaf, yielding, and elastic zones. The three zones were considered to all have resistances against shear stress. The basal coal seam is likely to become weak due to weight from the overlying strata, which may change the slope failure mode from circular to sliding along the weak layer. Numerical modeling was used to study the influence of the overlying strata and target time strength on the yielding zone development at the coal pillar ribs. The coefficients of the three zones were determined and substituted into the Mohr-Coulomb equation to obtain the time-dependent shear strength parameters. Subsequently, the influence of highwall mining on the slope stability was evaluated using the rigid body-limit equilibrium method (LEM). The optimized coal pillar width is determined to maximize the recovery rate without compromising the slope stability.

Shallow stability and parameter sensitivity analysis of soil slope with frame protection under rainfall seepage

Frame protection is a commonly used solution to maintain the shallow stability of soil slope under rainfall seepage. Currently, the frame structure's design is empirical, and its theoretical analysis method considering the influence of seepage is scarce. Based on the instability model of the infinite slope, the shallow stability calculation model of soil slope under the rectangular frame protection is established in this paper. The calculation results show that it is beneficial to maintain the shallow slope stability by reducing the skeleton spacing and increasing the cross-sectional size of the frame structure. Also, geometric parameters' sensitivity analysis of the frame structure is carried out based on the orthogonal experimental design methods. Therein, an optimal scheme evaluation function was constructed to balance the relationship between the safety factor and the construction material consumption. The calculation model and results included in this paper can guide the design of the rectangular frame protection to soil slope under rainfall seepage.

Traffic Safety Assessment of Highway Abnormal Indivisible Load Transport under Smoke-Free Regulations

A high proportion of truck drivers have smoking habits, especially for long-distance truck drivers, 90% of which have the habit of smoking. In recent years, some regulations are launched focus on the smoking behavior of drivers in the driving process. And the policies forces drivers to abandon the smoking habit. Abnormal indivisible load transport is crucial to the sustainable development of highway safety. In order to scientifically and effectively evaluate the traffic safety of highway abnormal indivisible load transportation, on the basis of extensive investiga of large transportation enterprises and management departments, combined with the method of UAV tracking and shooting video, the traffic variation features of outer profile size, load, dynamic characteristics and trajectory of abnormal indivisible load transport vehicles are obtained. Firstly, the meaning of abnormal in-divisible load transportation is defined. The traffic safety assessment of abnormal indivisible load transport is studied from the aspects of road accessibility and operation safety. Secondly, by ana-lyzing the jacking-up failure of abnormal indivisible load vehicles on convex curves, the sweeping space of the horizontal alignment, and rollover side slip conditions cross section, the road accessibility evaluation model of abnormal indivisible load vehicles under different highway alignment conditions is proposed. Thirdly, based on a certain binding strength, the constraint conditions for preventing the transverse and longitudinal sliding of the cargo are proposed, and the stability calculation method of the collapse point of the hydraulic trailer is determined. Finally, the feasibility and practicability of the safety evaluation method is verified by taking abnormal indivisible load transportation in Sichuan Province as an example. The achievements will lay a foundation for the necessary guidance of sustainable highway transport management. With the application of these technologies, the safety of abnormal indivisible load transport under smoke-free regulations can be guaranteed.

Failure of Rock Slopes With Intermittent Joints: Failure Process and Stability Calculation Models

Rock slopes with intermittent joints in open-pit mines are complex geological bodies composed of intact rock and discontinuous structural planes, and their stability analysis are necessary for mine disaster prevention. In this study, a series of base friction tests were performed to determine the failure process and displacement field evolution of rock slopes with intermittent joints using the speckle technique of a noncontact measurement system. Next, stability calculation models of the slopes were established from the energy perspective using the plastic limit analysis theory, and the effects of the joint inclination angle and coalescence coefficient of rock bridges on the slope stability were evaluated. The four main conclusions are as follows. (1) The failure of rock slopes with intermittent joints shows the feature of collapse-lower traction-upper push. (2) Based on the failure modes of rock bridges in slopes, the failure of rock slopes with intermittent joints could be divided into three types: tensile coalescence (Type A), shear coalescence (Type B), and tensile–shear coalescence (Type C). (3) Among the three slope types, the stability of the Type A slope is significantly influenced by rock cohesion, whereas that the Type B slope is significantly influenced by joint cohesion. The stability of the Type C slope is significantly influenced by the joint inclination angle and joint friction angle. (4) The local-stable slope is unstable while the first through-tensile crack in the zone of the potential sliding body higher than the critical instability height appeared. This study guides the stability evaluation and instability prediction of jointed rock slopes in open-pit mines.