An Analytical Elastic Solution for Right-Angle Trapezoidal Opening in Steeply Inclined Coal Seam

In the process of underground mining, steeply inclined rocks or coal seams are often encountered, forming the openings of right-angle trapezoid. According to the geological conditions of a mining project in China, an analytical elastic solution of stress and displacement around right-angle trapezoidal opening in a homogeneous, isotropic, and linear elastic geomaterial is presented, which is based on the evaluation of the conformal mapping representation by an appropriate numerical calculation and the complex potential functions. The different results from other shaped openings are shown as follows. In a right-angle trapezoidal opening, the maximum displacements of roof falling occur on the low side, while the most horizontal displacements on the low side are around the roof and the most horizontal displacements on the high side are around the middle of the high side in this opening. These results are also compared with the numerical calculations in FLAC software, illustrating that the solution may be easily applied to rock mechanics or rock engineering for understanding the deformation of floor heave and roof falling down. The solution is also suitable for optimum design of bolt supporting in a right-angle trapezoidal opening, which is different from the traditional concept of symmetrical bolt supporting. Finally, a methodology is proposed for the estimation of conformal mapping coefficients for a given cross-sectional shape of an opening without symmetrical axis.

Improving the Stability of the Directional Room G 31-33, Horizon 210 - East, Ocnele Mari-Coceneṣti Salt Mine, By Reinforcement with Anchors and Shotcrete

The rock salt deposit from Ocnele Mari - Coceneşti was mined by the method with rooms and small square pillars, at the levels + 226m and + 210m. Although the saline is not deep, certain instability phenomena (cracks, exfoliations) have occurred in the resistance structures (pillars, ceilings), especially in the G31-33 directional room, horizon 210E. These instability phenomena were also highlighted following the 3D finite element numerical modelling. In order to prevent the degradation of the mining excavations and the resistance structures, the affected surfaces were supported with anchors and reinforced shotcrete. The ceiling of the consolidated section of the G31-33 directional room, horizon 210E is monitored by the systematic measurement, on topographic landmarks mounted on the ceiling, of the vertical and horizontal displacements.

Effect of groundwater on the displacements of axially loaded pile in clayey soil

The displacement of a loaded pile could be vertical (axial) or horizontal (lateral); these displacements are sensitive to groundwater presence within the soil mass. This paper presents a theoretical study to investigate vertical and horizontal displacement of piles embedded in a clayey soil for different levels of groundwater under the ground surface. The study was performed using the commercial finite element package PLAXIS-3D. Three diameters of the concrete piles were considered: 0.5, 0.75 and 1 m, and were subjected to 1,000 kN axial load. The effect of 0, 5, 10, 15 and 20 m groundwater along the 20 m pile in length from the ground surface on the vertical and horizontal displacements was investigated. The results indicated that the vertical and horizontal displacements increase when the ground water level increases towards the base of pile. Also, there is a significant increase in the horizontal displacement up to 15 m of groundwater level from ground surface and decreased at levels from 15 to 20 m.

The model identification of buildings horizontal displacements with the use of a free geodetic network

The geodetic monitoring of engineering structures, their displacements, and deformations, carried out permanently or periodically, allows obtaining information on the technical condition of facilities. The achieved information enables determining the necessary changes in using objects and minimizing future errors in the similar object’s design. The measurement results are subject to geometric interpretation based on the determined displacement parameters of the object’s shape and the approximation of the vector displacement field. Due to the influence of random factors characterized by a change in time and varying intensity, the deformation measurements performed during the operation of the facilities are of great importance for the safety of structures and engineering structures. In actual tasks of determining the object’s deformation and building a geometric model of displacements, the dominant method is the differential method, the advantage of eliminating systematic errors in measurement results while maintaining the geometric structure of the measurement and control network. The displacement’s geometric model, built based on measurements and calculations, can build a dynamic model of a building object, additionally considering such causes of deformation as, for example, own and usable weight, wind pressure, changes in ambient temperature, or ground vibrations. The article proposes approaches using the free alignment of linear and angular observations made in a geodetic network to determine horizontal displacements of an engineering object. This method may be necessary to study displacements of various parts of the object, thus analyzing its deformation. Free alignment allows for an optimal fit of the equalized network into the approximate network by imposing additional conditions (compared to the classic least squares method) on the vector of estimates of increments to approximate coordinates and the value of the covariance matrix. As an example of applying the proposed approach, the actual data received from the geodetic monitoring of the building structure was used. The structure was a road viaduct located along Wojska Polskiego Street in Bydgoszcz. The object of measurements and analyses was represented by finite sets of fixed points, subject to periodic observations over two years. The authors tested the effectiveness of the proposed algorithm and compared the obtained results with the values of horizontal displacements, which were calculated based on the classic study of geodetic monitoring results using the least-squares method. The accuracy analysis of the obtained values of the geodetic network horizontal displacements using free alignment and the least-squares method was also performed. The results indicate the possibility of using the presented approach to identify the geometric model of horizontal displacements without losing the accuracy of their determination.

The Integration of Two Interferometric Radars for Measuring Dynamic Displacement of Bridges

Measurements of displacements of bridges under dynamic load are particularly difficult in the case of structures where access to the area under the tested structure is impossible. Then, remote measurement methods are preferred, such as interferometric radar. Interferometric radar has high accuracy when measuring displacement in the direction of its target axis. The problems appear when a bridge vibrates in two directions: horizontal (lateral or longitudinal) and vertical. The use of one radar to measure those vibrations may be impossible. This paper presents the application of a set of two interferometric radars to measure vertical vibration and horizontal longitudinal vibration with high accuracy. The method was positively verified by experimental tests on two railway bridges characterized by different levels of horizontal displacement. The accuracy of the radar measurements was tested by the direct measurement of vertical displacements using inductive gauges. In conclusion, in the case of vertical displacement measurements using one interferometric radar, the influence of horizontal displacements should be excluded. In the case of locating radars at the area of bridge supports, it is necessary to either use a set of two radars or first investigate the magnitude of possible horizontal displacements in relation to vertical displacements.

The Effects of Tidal Translation on Wave and Current Dynamics on a Barred Macrotidal Beach, Northern France

Barred macrotidal beaches are affected by continuous horizontal displacements of different hydrodynamic zones associated with wave transformation (shoaling, breaker and surf zones) due to significant tide-induced water level changes. A series of wave and current meters, complemented by a video imagery system, were deployed on a barred beach of northern France during a 6-day experiment in order to characterize the spatial and temporal variability of wave-induced processes across the beach. Wave and current spectral analyses and analyses of cross-shore current direction and asymmetry resulted in the identification of distinct hydrodynamic processes, including the development of infragravity waves and offshore-directed flows in the breaker and surf zones. Our results revealed a high spatial variability in the hydrodynamic processes across the beach, related to the bar-trough topography, as well as significant variations in the directions and intensity of cross-shore currents at fixed locations due to the horizontal translation of the different hydrodynamic zones resulting from continuous changes in water level due to tides.

Long term hydrological and environmental monitoring of the Stryi River using remote sensing data and GIS technologies

The proposed research sets the task of conducting monitoring aimed at determining the horizontal displacements of the channel of the Stryi River the largest right-bank tributary of the Dniester River. For this purpose, the river was zoned according to morphometric and hydrological characteristics. Three parts were identified, namely highland, piedmont and lowland ones, which radically vary in the nature of the flow and the amount of the displacement. The main research purpose consists in analyzing the impact of anthropogenic factors on the hydrological regime of the Stryi River, as well as studying the effect of the Ukrainian Carpathian Foredeep (UCF) and the Stryi Deep on the mode of horizontal displacements. The research object is processes occurring within the Stryi River channel. Considering main natural factors affecting the channel’s horizontal displacements, special attention is paid to the geological and sedimentological structures located in the region where the Stryi River and its tributaries flow; among the anthropogenic factors, deforestation and the extraction of building materials from the river channel are highlighted. Topographic, geological, soil maps and satellite images of various periods uploaded into ArcGIS software allowed us to monitor displacements observed for as long as 140 years ago. To monitoring the Stryi River channel displacements, such materials as topographic maps scaled 1: 75000 (Austrian period – 1874), 1: 100000 (Polish period – 1933, Soviet period – 1990); satellite images of Sentinel-2 (2019 and 2020 (after the flood)); a map of Quaternary sediments and a soil map scaled 1: 200000 were used. The Stryi River flows between two structures, i.e. the Skybovi Carpathians and the UCF. The right-bank tributaries (Bystrytsia, Limnitsia, Stryi, etc.), which begin in the Carpathians, cross the outer and inner boundaries of the UCF and are characterized by the stable river channel in its mountainous part, multi-braided in its piedmont part, as well as perennial and significant meandering within the Pre-Carpathian region. Lithological deposits have a significant impact at the mouth of the Stryi River. According to the research study results, displacements of up to 1,350m are measured in this area. The research includes an analysis of the influence of geological and sedimentological structures on the Stryi River displacement and the nature of its flow. It has been established that deforestation in the river basin, as well as unauthorized extraction of gravel materials, creates a significant environmental problem in this region. The results of monitoring of the channel deformation processes should be taken into account when solving problems related to river channel processes, namely the construction of hydraulic structures, the design of power transmission networks crossing rivers, the development of gas pipelines, the identification of hazardous flooding zones, the determination of consequences of destruction after floods, the establishment of boundaries of water protection zones, the management of recreational activities, monitoring of border lands and the establishment of an interstate border along rivers.

Temporal-Spatial Characteristics of Ground and Pile Responses to Twin Shield Tunneling in Clays

This paper investigates the temporal-spatial characteristics of ground displacements as well as vertical and horizontal displacements and axial forces in existing piles induced by twin shield tunneling in clays. To that end, a case study and three-dimensional (3D) finite element (FE) analysis were performed. Based on the in situ monitoring data from the presented twin tunneling case history with existing piles beneath, the adopted 3D FE method was validated to be competent to yield reasonable simulation results. The validated 3D FE method was then used to analyze the effects of the distance between the tunnel and the pile, the distance between tunnel faces, and the pile length on the horizontal and vertical displacements and axial stresses in piles. It was found that the horizontal displacement distribution forms along the pile shaft for the front piles are similar to that for the back piles, whereas the magnitudes of the horizontal displacements of the front piles are slightly larger than that of the back piles. The interactions between piles in the pile group provide protection of the middle piles in the pile group against twin tunneling effects. With a reduction in the distance between the tunnel and the pile, the pile displacements and stresses increase nonlinearly. With an increase in the distance between tunnel faces, the maximum positive pile displacements and the maximum and minimum axial pile stresses increase, while the maximum negative pile displacements and the difference between the maximum and minimum axial pile stresses decrease.