Numerical Simulation of the Shear Behaviour of Cement Grout

Cement grout is widely used in civil engineering and mining engineering. The shear behaviour of the cement grout plays an important role in determining the stability of the systems. To better understand the shear behaviour of the cement grout, numerical direct shear tests were conducted. Cylindrical cement grout samples with two different strengths were created and simulated. The numerical results were compared and validated with experimental results. It was found that, in the direct shear process, although the applied normal stress was constant, the normal stress on the contacted shear failure plane was variable. Before the shear strength point, the normal stress increased slightly. Then, it decreased gradually. Moreover, there was a nonuniform distribution of the normal stress on the contacted shear failure plane. This nonuniform distribution was more apparent when the shear displacement reached the shear strength point. Additionally, there was a shear stress distribution on the contacted shear failure plane. However, at the beginning of the direct shear test, the relative difference of the shear stresses was quite small. In this stage, the shear stress distribution can be assumed uniform on the contacted shear failure plane. However, once the shear displacement increased to around the shear strength point, the relative difference of the shear stresses was obvious. In this stage, there was an apparent nonuniform shear stress distribution on the contacted shear failure plane.

Design and analysis of plate anchors in sand

Plate anchors, as an efficient and reliable anchorage system, have been widely used to resist uplift forces produced by structures, such as transmission towers, offshore platforms, submerged pipelines, and tunnels. In order to design a plate anchor it is important to know the factors which influence the design and uplift behavior of anchors embedded in sand. In this report a number of model uplift tests and numerical investigations made by different authors are described and based on these readings the uplift behavior of anchors in sand is explored and anchor's design procedure is described. In addition, basic anchor types, failure modes in anchors, and design codes are mentioned. Based on this study, it is found that the failure plane and uplift capacity is significantly influenced by the soil density and embedment depth. Therefore, it is concluded that the influence of sand density and embedment depth should be considered in anchor design.

Design and analysis of plate anchors in sand

Plate anchors, as an efficient and reliable anchorage system, have been widely used to resist uplift forces produced by structures, such as transmission towers, offshore platforms, submerged pipelines, and tunnels. In order to design a plate anchor it is important to know the factors which influence the design and uplift behavior of anchors embedded in sand. In this report a number of model uplift tests and numerical investigations made by different authors are described and based on these readings the uplift behavior of anchors in sand is explored and anchor's design procedure is described. In addition, basic anchor types, failure modes in anchors, and design codes are mentioned. Based on this study, it is found that the failure plane and uplift capacity is significantly influenced by the soil density and embedment depth. Therefore, it is concluded that the influence of sand density and embedment depth should be considered in anchor design.

Shear Behavior of Concrete Encased Steel Truss Composite Girders

In this study, experimental tests were performed to evaluate the shear performance of encased steel truss (EST) composite girders that can resist loads at construction and composite stages. Four full-scale EST composite girders were fabricated, where the truss type (Pratt truss and Warren truss) and presence of stirrups were set as main test variables. The test results showed that in specimens applied with the Pratt truss, horizontal shear cracking occurring along the interface between concrete and steel was the dominant failure mode. Based on the crack pattern and failure plane observed from the test, the horizontal shear strengths of the Pratt truss specimens were calculated, which provided conservative results. On the other hand, in the specimens with the Warren truss inside, the strengths of the specimens were governed by the shear failure occurring in the screw rod connecting the truss elements prior to the yielding of the diagonal member. The shear strengths of the Warren truss specimens calculated based on the shear failure of the screw rod were similar to that obtained from the test.

2-D Cross-Plot Model Analysis Using Integrated Geophysical Methods for Landslides Assessment

The large or small scale of a landslide is a natural, widespread process, resulting from the downward and outward movement of slope-forming materials, such as sculpting the landscape. Characterized landslide material and properties’ inhomogeneities conditions become a challenge as the process required the availability of a wide range of data, observations, and measurements with an evaluation of geological and hydrological conditions. Detailed investigations represent an essential component of the landslide risk mitigation process, relying on subsurface investigations, discrete subsurface sampling, and laboratory tests. To extend this approach, seismic refraction and two-dimensional (2-D) resistivity were utilized to study the landslides activities in Ulu Yam. The cross-plot analysis was introduced to integrate the geophysical results based on the criteria of the model. Velocity distributions from seismic refraction revealed the stiffness of the soil, where weak zones identified with values of Vp ≤ 1200 m/s, defined as threshold frequency for failure to occur. The 2-D resistivity shows that the weak zones were identified with resistivity values of <1200 Ωm. The 2-D cross-plot model gives a comprehensive interpretation where a low velocity and resistivity value represents the failure plane of materials to failure. The volume of mass sliding was calculated based on retrieved information from the model.

Landslide in rocks of Jodhpur Group at Masuria Hill in Jodhpur, Western Rajasthan, India: Its causes and threat to significant Georesources

The ever first disastrous landslide at Masuria Hill (MH) damaged many houses and properties on 4th October 2019 in surrounding residential colonies of Masuria area in the Jodhpur city, Western Rajasthan India. Present landslide not only created panic among people but also damaged properties and significant georesources which is a serious concern for future. Geologically, MH is represented by rhyolite of Malani igneous suite (MIS) of Cryogenian age which is overlain by siliciclastic rocks of Jodhpur Group (JG) of Ediacaran age of Marwar Supergroup (MSG). Landslide occur in horizontally disposed rocks of Umed Bhawan Formation (UBF) of JG. UBF is divided into 4-18m thick clay dominated soft sediments zone with sheet and release joints at the base. It is followed by 24-72m thick rigid sand zone having orthogonal jointing. This disposition of soft and rigid pattern of sedimentation of UBF is identified as the key horizons responsible for the landslide with shale horizon as the failure plane. Causes of landslide can be explain based on the model of BPSZ (Bedding Parallel Shear Zone). BPSZ is attributed to three main mechanisms: liquefaction, mass wasting and shear stresses that caused the landslide at MH. Study further reveal that residential area surrounding MH and other seven hills having similar geological disposition are under great threat to future landslide in Jodhpur. Paper also embodies characteristics of georesources having educational and cultural values which are under great threat to landslide along with appropriate hazard mitigation measures.

An Optimization of the Analytical Method for Determining the Flexural Toppling Failure Plane

According to the results of the physical model tests, the failure plane of an anaclinal layered rock slope was a linear-type plane at an angle above the plane normal to the discontinuities, and the failure mode of rock strata was bending tension. However, the shear failure occurred near the slope toe, the effects of the cohesion of the discontinuities on the stability of the slope, and the contribution of tangential force to cross-section axial force were neglected in such studies. Moreover, none of the experts had developed a rigorously theoretical method for determining the angle between the failure plane and the plane normal to the discontinuities. This paper was initiated for the purpose of solving the problems described above. With the cantilever beam model and a step-by-step analytical method, an optimization of the analytical method for determining the flexural toppling failure plane based on the limit equilibrium theory was developed and the corresponding formulations were derived. Based on the present computational framework, comparisons with other studies were carried out by taking a slate slope in South Anhui in China and a rock slope facing the Tehran-Chalus Road near the Amir-Kabir Dam Lake in Iran. Furthermore, the sensitivity analyses of the parameters used in the calculation process of the failure angle of the slate slope in South Anhui in China were performed. The results demonstrated that the failure plane and the safety factor of the stability obtained with the presented method were credible, which verified the proposed method. The dip angle of the slope, the dip angle of the rock stratum, and the friction angle of the discontinuities were the controlling factors for the overall failure of the slate slope in South Anhui in China.

Behaviour of Parallel Bamboo Strand Lumber under compression loading – an experimental study

This paper investigates the compression behaviour of 18 Parallel Bamboo Strand Lumber specimens. 25 mm × 25 mm square specimens with varying heights and fibre orientations were tested. Test results indicated typical 5-stage failure path, and a 45º failure plane in all specimens when the compression load was applied parallel to the fibres. Specimen height did not affect the ultimate load carrying capacities but showed considerable influence on the initial stiffness as well as the post-ultimate loading regime. Experimental results showed that the deformation ratio and the energy absorption ratio for longer specimens were not affected by fibre orientations.

Zum Nachweis der Standsicherheit in der tiefen Gleitfuge bei erhöhtem aktivem Erddruck/On the verification of stability at the lower failure plane with increased active earth pressure

Zusammenfassung Der Nachweis der Standsicherheit in der tiefen Gleitfuge ist einer der Standardnachweise für eine verankerte Baugrubenwand. Dieser wird derzeit mit einem Nachweisverfahren 2 laut Eurocode 7 geführt, wobei die mögliche Ankerkraft nach Kranz als Widerstand definiert und mit der vorhandenen Ankerkraft als Beanspruchung verglichen wird. Alternativ kann man die Beanspruchung und den Widerstand in der tiefen Gleitfuge miteinander vergleichen. Bei Berechnungen mit nicht erhöhten aktiven Erddrücken liefern beide Methoden mit den aktuell festgelegten Teilsicherheits- beiwerten ähnliche erforderliche Ankerlängen. In diesem Beitrag wird gezeigt, dass die aktuelle Sicherheitsbetrachtung über die mögliche Ankerkraft nach Kranz im Fall der Berücksichtigung erhöhter aktiver Erddrücke für bestimmte Geometrien des Bruchkörpers mechanisch widersprüchliche Ergebnisse liefert. Im Gegensatz dazu liefert die Sicherheitsbetrachtung über die Beanspruchung und den Widerstand in der tiefen Gleitfuge mechanisch konsistente Ergebnisse.

Experimental Study on the Shear Behavior of Bolted Concrete Blocks with Oblique Shear Test

The shear behavior of concrete blocks reinforced by fully grouted bolts with different diameters was studied in this paper. More than 90 intact cubic samples (100 mm × 100 mm × 100 mm) with bolts ranging from 2 mm to 5 mm in diameter were tested at a constant stain rate of 0.5 mm/min. An oblique shear apparatus, which could simultaneously apply shear and normal force on tested samples at three slope angles (53°, 58°, and 63°) of a predetermined shear plane, was employed. The results indicate that the bolt has no evident influence on the shear behavior of intact concrete blocks at the prepeak shear strength stage. The bolt could significantly reduce the shear strength drop in the peak shear strength of the concrete block and contribute to reserving the residual shear strength of concrete blocks, especially at steep slope angles of the shear failure plane. The shear resistance provided by the bolt to the concrete block at the residual shear slip stage has a positive relationship with the diameter. The bolt with a larger diameter inflected in the vicinity of the shear failure plane of concrete block at the postpeak shear strength stage; additional normal force and direct shear resistance could still be persistently provided. Two empirical equations of the apparent cohesion and apparent internal angle of the bolted concrete block were obtained by linear regression considering rb, which is the ratio of the cross-sectional area of the bolt to that of the bolted concrete block.