Rigid Retaining Research Articles

Active Earth Pressure Characteristics of Light Weight Soil with EPS Particles Behind Rigid Retaining Wall

Active Earth Pressure Characteristics of Light Weight Soil with EPS Particles Behind Rigid Retaining Wall

Design and Validation of Soft Sliding Structure with Adjustable Stiffness for Ankle Sprain Prevention.

This study presents the design and validation of a soft sliding stiffness structure with a soft-rigid layer sliding mechanism. It aims to mitigate ankle sprains and address the progression of chronic ankle instability by providing stiffness support. The soft-rigid layer sliding mechanism of the structure is designed to achieve a wide range of stiffness while maintaining a compact form factor. The structure incorporates rigid retainer pieces within each layer, which allows for sliding within a hollow cuboid structure and enables modulation of stiffness. An analytical model is presented to investigate the variations in stiffness resulting from the different sliding states. The stiffness characteristics of the structure were validated through both bench tests and human subject tests. The gradual sliding of the structure's layer resulted in an increase in stiffness, aligning with the analytical model's predictions. At the most rigid stage (0% alignment), the stiffness exhibited a significant increase of 111.1% compared to the most flexible stage (100% alignment). Additionally, the human subject testing demonstrated a stiffness increase of up to 93.8%. These results underscore the potential applicability of the soft sliding structure in ankle support applications.

Assessment of Analytical Solutions for Calculating Lateral Earth Pressures Behind Rigid Retaining Walls Under Translational Movement

Assessment of Analytical Solutions for Calculating Lateral Earth Pressures Behind Rigid Retaining Walls Under Translational Movement

Investigation into the Displacement-Dependent Lateral Earth Pressure on the Rigid Retaining Wall with Different Modes of Movement: Modeling with the Trigonometric Function

Investigation into the Displacement-Dependent Lateral Earth Pressure on the Rigid Retaining Wall with Different Modes of Movement: Modeling with the Trigonometric Function

Analysis of Active Earth Pressure Behind Rigid Retaining Walls Considering Curved Slip Surface

Analysis of Active Earth Pressure Behind Rigid Retaining Walls Considering Curved Slip Surface

Calculation of Nonlimit Active Earth Pressure against Rigid Retaining Wall Rotating about Base

A retaining wall with sandy fill was considered as the research object in order to study the nonlimiting active earth pressure under the rotation about the base (RB mode). Rankine’s and Coulomb’s earth pressure theories are no longer applicable to the above conditions (RB mode and nonlimiting active earth pressure). In order to improve the traditional earth pressure calculation methods (Rankine and Coulomb), a calculation method using curvilinear thin layer elements is presented with overall considerations of wall displacement, soil arching effect, and friction angle exertion coefficient to deduce the nonlimit active earth pressure under RB. Additionally, the calculation results were in good agreement with model test data (from Fang and Smita). Moreover, a parametric analysis was carried out. It was revealed that the developed value of the shear strength decreased with the depth, and the active earth pressure distribution curve was linear and nonlinear in the upper and lower halves, respectively.

Numerical Investigation of Impact Characteristics of Rigid Retaining Wall for Blocking Landslides: A Case Study of the Shum Wan Road Landslide

Landslides pose a serious threat to the downstream infrastructure and personnel safety. For situations where the location of possible landslides is difficult to determine, or the potential landslides areas are widely distributed and scattered, passive protective structural measures need to be adopted to relieve the threat of landslides. Taking the Shum Wan Road landslide as an example, the discrete element method was used to reproduce and analyze the landslide movement. On this basis, this study conducts a further numerical investigation on the impact characteristics of the rigid retaining wall used to block landslides. The results show that the numerical back analysis can well represent the evolution of the landslide, and the numerical results are in good agreement with the actual situation, thus confirming its correctness and effectiveness. Under the condition of setting a rigid retaining wall, the landslide can be effectively blocked and form a final deposition behind the retaining wall. The impact on the rigid retaining wall varies with time, and the distribution of the impact in space is also uneven. Through the statistical analysis of the contact forces on the retaining wall, the distributions of static and peak stresses on the retaining wall can be obtained. Compared with the static stability, the spatial distribution of dynamic impact is more difficult to predict, especially the area of the peak impact has a significant influence on the design. Numerical investigation can efficiently and reliably provide abundant information of static stress and dynamic impact on the rigid retaining wall, which can provide important reference for the optimal design of the rigid retaining wall structure.

Long-term observation of periodontal condition following placement of removable partial dentures with rigid retainers and major connector in patients with/without diabetes: A retrospective study.

This retrospective study evaluated the periodontal tissues of the abutment teeth of removable partial dentures (RPDs) with rigid retainers and major connectors in patients with and without type 2 diabetes mellitus (T2D). A total of 313 patients who had been treated with RPDs, including rigid retainers and major connectors, were divided into two groups: T2D and non-T2D. The periodontal parameters and radiographic bone heights of the abutment teeth were evaluated at baseline and at a 5-year examination during supportive periodontal therapy (SPT). For patients with accessible standardized radiographs, bone density was analyzed based on the gray level (GL) using digital subtraction radiography (n = 83). Overall, 739 abutment teeth (86 in the T2D group) of 235 patients (25 in the T2D group) were analyzed, and 95.0% (94.2% in the T2D group, and 95.2% in the non-T2D group) were maintained. The mean probing pocket depth significantly increased in both groups (p < 0.001). There were significant changes in the radiographic bone height (p = 0.038) and GL on the side of the denture base area (p = 0.048) in the T2D group compared to those in the non-T2D group. Regardless of T2D, RPDs with rigid retainers and major connectors could prevent the progression of periodontal disease and successfully maintain most of the abutment teeth during 5-years of SPT. However, T2D may be significantly associated with loss of bone height reduction and density on the side of the denture base area.

Three-dimensional analysis of the posttreatment displacements of mandibular anterior teeth with rigid and flexible lingual retainers

The purpose of this study was to analyze any posttreatment changes in the positions of mandibular anterior teeth retained by 2 different fixed retention methods (rigid or flexible) and their effectiveness in minimizing postorthodontic tooth movement. Thirty patients were selected for inclusion in this retrospective study. Group I consisted of 15 patients with 0.032-in stainless steel rigid retainers bonded to canines only. Group II consisted of 15 patients with 0.0215-in twisted stainless steel flexible retainer bonded to all mandibular anterior teeth. Geomagic Control (3DS Systems, Rock Hill, SC) software was used to quantify the changes between selected points. Paired t test was used for intragroup comparisons in all 3 coordinates, and an independent-sample t test was used for intergroup comparison. In the transverse dimension, significant intergroup differences were found in displacements of distoincisal points of the right lateral (P<0.05) and left central incisors (P<0.01). In the sagittal dimension, significant intergroup differences were found in the displacements of mesioincisal point of the right central incisor (P<0.05) and distoincisal point of the left central incisor (P<0.01). Examining total displacement, there were significant intergroup differences in mesioincisal point on the right central incisor, distoincisal point on the left lateral incisor (P<0.05). Our results suggested that central incisor contacts were more likely to shift with the rigid retainers, especially in sagittal and transverse dimensions. However, no statistically or clinically significant changes were noted in the third-order or vertical positions of the teeth with either retention method.

ЛАБОРАТОРНОЕ ИЗУЧЕНИЕ АДГЕЗИВНЫХ МОСТОВИДНЫХ ПРОТЕЗОВ, ЗАМЕЩАЮЩИХ ВКЛЮЧЕННЫЕ ДЕФЕКТЫ В БОКОВЫХ ОТДЕЛАХ ЗУБНЫХ РЯДОВ. ЧАСТЬ 1

Background. Developed at the end of the 20th century, resin-bonded fixed partial dentures are now a real alternative to traditional bridges and intraosseous implants. The mean survival rate of conventional fixed partial dentures clearly exceeds the mean survival rate of adhesive fixed partial dentures. Debonding of fixed/fixed resin-bonded fixed partial dentures is associated with the difference in the natural mobility of the abutment teeth. Therefore, the fixed/movable resin-bonded fixed partial dentures are preferable.&#x0D; Objectives — to study the stress distribution in fixed/movable resin-bonded fixed partial dentures RBFPD using finite element analysis. &#x0D; Methods. The finite element method was used to preliminary estimate the stress distribution pattern in fixed/movable resin-bonded fixed partial dentures (metal or fiberglass-composite). The calculation was carried out using special programs (Ansys 12.2 Inc. Ansys — USA and AWP 3 D Studio — Russia).&#x0D; Results. The medial area of stresses is located only in the contact zone of the occlusal rest in the quantitative range of 32-60 N/mm2. The distal area of stresses corresponds to the distal connector, being approximately in the same range — 40-65 N/mm2. In the case of a metal retainer, the stresses also apply to it — 4-37 N/mm2. In the case of a fiber-composite retainer, stresses are practically not applied to it — 1-14 N/mm2.&#x0D; Conclusions. Analysis of the stress distribution pattern for the fixed/movable resin-bonded fixed partial dentures, obtained by the finite element method, confirmed: 1) the expediency of shortening the minor retainer 2) the choice of a rigid metal (possibly ceramic) major retainer instead of a weakly rigid fiber-composite major retainer.

Earth Pressures Mobilised in Dry Sand with Active Rigid Retaining Wall Movement

A series of centrifuge tests was conducted to explore the earth pressures mobilised in loose and dense sand for a complete set of active movement modes of a rigid retaining wall: rotation about the base, translation and rotation about the top. Earth pressures behind the wall were measured by a Tekscan pressure mapping system. This paper reveals that earth pressures at all depths decrease simultaneously with active wall rotation about the base, while those in shallow layers can increase with active wall translation and rotation about the top. A linkage between earth pressures and shear strains was built as a simplified constitutive law, together with deformation mechanisms, allowing designers to predict flexible wall deflections during construction as well as ultimate collapse.

Calculation of Passive Earth Pressure on Rigid Retaining Wall Affected by Seepage and Soil Arching

Seepage and soil arching are commonly encountered in the soil behind a rigid retaining wall, so the influence of these factors should be considered when calculating the earth pressure of the retaining wall. In this paper, behind a rigid retaining wall the steady seepage field was analyzed, the soil arching was also presented assuming the parabola soil arching, then improved formula of passive earth pressure on rigid retaining wall is obtained based on the horizontal differential element method. The result showed that the calculation of the passive earth pressure by the horizontal differential element method is consistent with the Coulomb’s earth pressure theory. Considering the seepage effect will reduce the passive earth pressure, while considering the soil arching effect will not change the passive earth pressure. The height of application of passive force from bottom is less than 1/3 of the height of the retaining wal. Considering the soil arching, the height of application of passive force from bottom is moved down, and the height of application of passive force from bottom is moved up by considering the seepage.

Estimation of Active Earth Pressure Against Rigid Retaining Walls Considering Soil Arching Effects and Intermediate Principal Stress

Abstract In this study, a novel analytical approach is proposed for the calculation of active earth pressure on rigid retaining walls considering the influence of intermediate principal stress and ...

A Strain Dependent Approach for Seismic Stability Assessment of Rigid Retaining Wall

A new method is proposed to evaluate the seismic stability of a rigid retaining wall undergoing translation or rotational failure. In the present method, strain-dependent dynamic properties are used to assess the seismic stability of rigid retaining walls against sliding and overturning failure conditions. The effect of foundation soil properties on the stability of retaining walls is also considered. From the parametric study, it is observed that the foundation soil properties have a significant effect on both sliding and rotational stability of rigid retaining walls. This can be attributed to the use of strain-dependent dynamic properties and the consideration of foundation soil properties. The predictions of the proposed method are compared and verified against the results from other methods proposed in the past. The percentage increase in the results compared to the existing literature is a maximum of 10 and 28% for rigid (bedrock) and flexible (sand deposit) foundation, respectively.

Slip Surface and Active Earth Pressure of Cohesionless Narrow Backfill behind Rigid Retaining Walls under Translation Movement Mode

Abstract A slip-failure surface forms in the backfill soil upon sufficient yielding or movement of the wall that retains the backfill soil. The shape of the slip-failure surface plays an important ...

Analytical Solution for Rigid Retaining Structure Under Asymmetric Excavation in Cohesionless Soil

Analytical Solution for Rigid Retaining Structure Under Asymmetric Excavation in Cohesionless Soil

Active Earth Pressure on Rigid Retaining Walls Built Near Rock Faces

Abstract Rock faces prevent adequate calculation of the active earth pressure of retaining wall near rock faces via the Coulomb and Rankine theories. The research is based on differential slice met...

Active Earth Pressure against Rigid Retaining Walls for Finite Soils in Sloping Condition considering Shear Stress and Soil Arching Effect

The horizontal differential layer element method was used to study the active earth pressure of the finite‐width soil formed by the rigid retaining wall for the embankment or adjacent foundation pits. The cohesionless soil was taken as the research object, and the soil arch theory was introduced based on the translation mode of rigid retaining wall and the linear sliding fracture surface. The minor principal stress line was assumed as circular, considering the deflected principal stress as soil arching effect. The shear stress between level soil layers in the failure wedge was calculated, and the differential level layer method was modified. Then, the theoretical formula of the active earth pressure, the resultant earth pressure, and the point of application of resultant earth pressure were obtained using this revised method. The predictions by the proposed formula were compared with the existing methods combined with the cases. It is shown that the resultant finite pressure increases gradually and approaches to Coulomb active earth pressure values when the soil is infinite, with the increase of the ratios of the backfill width to height. Moreover, the horizontal pressure for limited soils is distributed nonlinearly along the wall height. Considering the shear stress between level soil layers and the soil arching effect, the position of application point of the resultant active earth pressure by the proposed formulation is higher than that of Coulomb’s solution. The wall is rougher, and the resultant pressure will be smaller. The application point distance from the bottom of the wall will increase. Finally, an experiment was conducted to verify the distribution of the active earth pressure for finite soil against rigid retaining wall, and the research results agree well with those of the experimented observations.

Experimental Study on the Active Earth Pressure of Narrow Cohesionless Backfills against Rigid Retaining Wall under the Translation Mode

In engineering, the new retaining walls are often constructed near the existing structure owing to the space limitation. The backfill behind the retaining wall is narrow, which causes an overestimation in the active earth pressure by using Coulomb’s earth pressure theory. In previous studies, experimental observations for the failure modes of narrow backfills are still rare. To confirm the failure mode of the narrow backfill, the experimental method and the geotechnical particle image velocimetry method are employed to observe the active failure process of the cohesionless narrow backfill with various widths under the translation mode. The experimental results revealed that the decrease in the length of the backfill width led to the increase in the inclined angle of the sliding surface. When the backfill width was sufficiently small, the sliding surface developed from the wall toe to another wall face, and then another sliding surface occurred as a reflection. In addition, the active earth pressure of the narrow backfill is significantly smaller than that calculated using Coulomb’s method. The active failure calculation models are established based on the experimental results. The active earth pressure of the narrow cohesionless backfill under the translation mode is derived by using the limit equilibrium methods. The proposed method was validated by comparing with the previous method and the experimental data.

Active Earth Pressure of Narrow Granular Backfill against Rigid Retaining Wall Near Rock Face under Translation Mode

AbstractWhen a retaining wall is built near a building or a mountain, the backfill width is often limited. It limits the use of the classical theoretical formula based on the assumption of an infin...