Experimental Study on Stiffness Softening of Soil-Rock Mixture Backfill under Metro Train Cyclic Load

Due to the thick soil layer, short backfill time, and low degree of consolidation of the soil-rock mixture backfill in Chongqing city, metro train tunnels passing through this type of strata are prone to large settlements during operation, which greatly affects the stability of the tunnel and the safety of metro train operations. In response to this problem, the dynamic triaxial test of the soil-rock mixture backfill under cyclic loading was carried out to study the dynamic characteristics of the soil-rock mixture backfill under cyclic loading. The effect of initial consolidation degree, effective consolidation confining pressure, and rock content on the stiffness softening of soil-rock mixture backfill was analyzed. The results show that the initial consolidation degree, effective consolidation confining pressure, and rock content are all important factors affecting the stiffness of soil-rock mixture backfill under cyclic loading. As the number of cycles increases, the lower the initial consolidation degree and effective consolidation confining pressure, the faster the attenuation of the softening index, and the larger the amplitude. As the rock content increases, the softening index increases and the stiffness of the backfill changes from softening to hardening. Based on the test data, the softening-hardening model of the soil-rock mixture is established, which is in good agreement with the field test results. This study can provide a reference for predicting and controlling the postconstruction settlement of the metro tunnel in the soil-rock mixture backfill.

ANALISIS DERAJAT KONSOLIDASI BERDASARKAN HASIL PEMBACAAN PIEZOMETER PADA PROYEK TOL TRANS SUMATERA

The development of toll road or expressway infrastructure in Indonesia is urgently needed because it can reduce inefficiencies due to congestion on main sections, as well as to improve the process of distribution of goods and services, especially in areas with high levels of development. Transportation infrastructure development on soft soils often experiences consolidation decline problems. Soft soil has a high moisture content and low bearing capacity. If the soft soil is saturated with water, it means that the water cannot be fully dissipated, causing the soil to take a long time to consolidate. If the construction work does not begin with land improvement, the construction has the potential to suffer damage before the planned age. To anticipate this, an alternative that can be done is to repair the soil with prefabricated vertical drain (PVD) and vacuum preloading. This study aims to determine the degree of consolidation based on the piezometer reading and to make initial predictions. As for the results of this study there is a difference of 5.79% in the degree of assessment from the results of theoretical calculations with the piezometer reading.Pembangunan infrastruktur jalan tol atau jalan bebas hambatan di Indonesia sangat dibutuhkan karena dapat mengurangi inefisiensi akibat kemacetan pada ruas utama, serta untuk meningkatkan proses distribusi barang dan jasa terutama di wilayah yang sudah tinggi tingkat perkembangannya. Pembangunan infrastruktur transportasi pada tanah lunak sering mengalami masalah penurunan konsolidasi. Tanah lunak memiliki kadar air yang tinggi dan daya dukung yang rendah. Jika tanah lunak jenuh air mengakibatkan air tidak dapat terdispasi secara penuh menyebabkan tanah membutuhkan waktu yang lama untuk terkonsolidasi. Apabila pekerjaan konstruksi tidak diawali dengan perbaikan tanah maka konstruksi tersebut berpotensi mengalami kerusakan sebelum umur yang telah direncanakan. Untuk mengantisipasi hal tersebut alternatif yang dapat dilakukan adalah melakukan perbaikan tanah dengan prefabricated vertical drain (PVD) dan vacuum preloading. Penelitian ini bertujuan untuk mengetahui besar derajat konsolidasi berdasarkan pembacaan piezometer serta melakukan prediksi awal. Adapun hasil dari penelitian ini terdapat perbedaan 5,79% derajat konsolidasi dari hasil perhitungan teoritis dengan pembacaan piezometer.

A simple approach to predict settlement due to constant rate loading in clays

Classical theory of consolidation was conceived considering loads instantaneously applied. Since then, researchers have addressed this issue by suggesting graphical and/or analytical solutions to incorporate different time-depending load schemes. The simplest alternative is to assume a linearly increasing load. Another approach to predict the average degree of consolidation caused by a constant rate loading is based on instantaneous excess pore pressures during and at the end of construction. This technical note explains why and how this approach leads to substantial errors after the end of construction. A corrected solution is then proposed, based on the concept of superposition of effects. The final set of equations agree with the theoretical ones. A new simple approximate methodology is also presented. Numerical examples using the proposed approach showed an excellent agreement with the analytical solution. The validity of this new approach was also proven by reproducing oedometer test results with a good agreement.

Numerical Analysis of Staged Construction of an Embankment on Soft Soil

The objective of this study was to predict the excess pore pressure and settlement of an embankment over soft ground, treated with vertical drain, through numerical analysis of staged construction. To carry out finite element analysis, numerical modeling software PLAXIS 3D was used. The practical demonstration was demonstrated by validating two case studies; the first one was a trial embankment at the Krishnapatnam Ultra Mega Power Project in Nellore, Andhra Pradesh, India and the second one was the Second Bangkok International Airport or Suvarnabhumi Airport, about 30 km from the city of Bangkok, Thailand. After the successful validation of the program, detailed finite element modelling of an embankment resting on soft soil was conducted. Moreover, the degree of consolidation and factor of safety were also determined. There was rapid dissipation of excess pore pressure and maximum settlement at the mid-height of the embankment. In contrast, the dissipation of excess pore pressure was very slow just below the embankment and it increased with the increment of the depth of the clay layer. Moreover, with the rise of the distance from the centre of the embankment, the dissipation of the excess pore pressure also raised and took less time, the settlement also increased.

Model Test and Theoretical Analysis of New and Old Embankments Differential Settlement Considering Lateral Deformation

In the embankment widening project, the new embankment will produce large deformation due to the low degree of consolidation, which will affect the stability of the embankment. Obtaining the settlement law of embankment is the premise to ensure the stability of the embankment. In this paper, the deformation law of the new embankment is studied through the embankment model test, and the settlement calculation method of the new embankment is proposed. The model test results show that the new and old embankments have a large settlement difference during the loading process, and the maximum settlement of the new embankment is twice that of the old embankment. The lateral deformation of the new embankment is directly proportional to the vertical deformation, sliding occurs under the ultimate load, and the bearing capacity is lost. Based on the one-dimensional calculation method, the lateral deformation coefficient is introduced, and the two-dimensional embankment settlement formula is obtained. The new embankment is meshed, and the deformation of each node is calculated by the formula, and the difference between the settlement and the model test data is 6.2%, which proves the feasibility and accuracy of the calculation method.

Estimation of genealogical lines of cattle of the Kazakh white-headed breed

An assessment of economically useful traits and external conformation of the Kazakh whiteheaded cows of the main genealogical lines, bred in the farms of the Altai Territory, was carried out. For the analysis, indicators of economically useful traits and conformation of first-calf heifers and full-aged cows of the Kazakh white-headed breed were used: live weight, measurements, total score for conformation, milk production. It was established that first-calf heifers of Zamok 3035 line surpass their herdmates in chest girth, and heifers of Zadorny 1325 and Korol 13682 lines are superior in oblique body length. Cows of Peon 29 line are inferior to their peers in live weight. The best indicators in live weight were noted in full-aged cows of Zadorny 1325 line, in milk yield – in Korol 13682 line. In general, there were no significant differences in most animal traits between the lines assessed. Analysis of full-aged cows belonging to the lines of Zamok 3035, Korol 13682, Zadorny 1325 showed that they surpass their herdmates in live weight, the lines of Korol 13682 – in milk yield. The study of the coefficients of heritability showed a low level of influence of the genotype on the variability of the main traits. This fact may indicate a high degree of consolidation of the Kazakh white-headed breed. In the breeding work with this breed, it is necessary to make wider use of sires belonging to the lines of Zadorny 1325, Zamok 3035. Particular attention should be paid to the rotation of genealogical groups. It is recommended to use new unrelated animals from other regions to increase the genetic variability of traits in herds. In order to do this, selection should be carried out in accordance with the grading requirements and selection parameters calculated for a particular farm.

One-Dimensional Consolidation of Viscoelastic Soils Incorporating Caputo-Fabrizio Fractional Derivative

In this paper, the Caputo-Fabrizio fractional derivative is introduced to investigate the one-dimensional consolidation behavior of viscoelastic soils. Using the Caputo-Fabrizio operator, a novel four-element fractional-derivative model is proposed to capture the viscoelastic properties of the soils, and further the one-dimensional consolidation equation is derived to simulate the consolidation behavior of the soils. Using the techniques of eigenfunction expansion and Laplace transform, a series of analytical solutions are derived to calculate the excess pore-water pressure and the average degree of consolidation of the soils. The total vertical stress in the soil is assumed to change linearly with depth, and its distribution patterns are classified to rectangular pattern, trapezoidal pattern and inverse trapezoidal pattern. Four loading types including instantaneous loading, ramp loading, sinusoidal loading and general cyclic loading are considered. Then, a comparison for several special cases is presented to verify the correctness of the proposed solutions through comparing with existing theories. Moreover, two examples considering ramp and sinusoidal loadings are given to study the consolidation behavior of the viscoelastic soils incorporating the Caputo-Fabrizio fractional derivative.

Theoretical and practical aspects of domestication of common catfish (Silurus glanis, L.)

The article discusses some aspects of the domestication of common catfish (Silurus glanis) in the conditions of cyprinid fish farms. Under the pressure of selection and directed cultivation in pond conditions of carp fish farms, changes in ethological, morphological, and physiological indicators are observed. The variability of the majority of morphological indicators and development indices (8–14%) indicates a high degree of consolidation of the resulting breeding offspring and indicates the completion of the first stage of domestication in the conditions of fish-breeding carp farms. Physiological and biochemical assessment of different age categories of catfish showed low variability of physiological indicators. it Can be assumed that the decrease in the coefficient of variability is a consequence of domestication. Studies of the immunological status have shown its optimal level, which allows us to accept the obtained indicators as indicative standards for evaluating brood flocks and their offspring. There was a significant increase in the body weight of commercial three-year-olds of the 4th breeding generation, compared with the first generation. It is established that the reproduction of catfish planted in carp summer-fallow ponds is more successful than in natural reservoirs, since ponds of this category are often small, well-warmed, which contributes to the rapid maturation of producers and the development of caviar. When growing in pond conditions for 2–3 generations, changes in behavioral reactions were noted — there was a decrease in aggressiveness and the development of conditioned reflexes to the specified food objects. The level of food availability affects the metabolism and maturation period, so along with the use of the natural feed base of the pond, it is recommended to use additional feeding and directed formation of the natural feed base.

Strategy oriented to strengthen the college work of teachers for the benefit of the consolidation of Academic Corps

The present work aims to show a strategy aimed at strengthening the academic staff through the creation of collegiate work groups which in the Mexican context are called Academic Corps (CA); the foregoing based on its strategic planning, collegiate work, relevance of the members of the CA, as well as the impact of its Lines of Generation and Application of Knowledge (LGAC) in the Educational Programs of the Faculty of Mechanical and Electrical Engineering, for which which proposes an academic-administrative structure that favors institutional achievements through the elevation of its indicators, where in the first instance a detailed analytical method of how many full-time professors participate in CA and the description of their LGAC, historical of academic corps by educational program and in what degree of consolidation they are found, in conclusion, different strategies were implemented promoting the increase of consolidated and consolidating academic corps , and their dissemination through means of recognized prestige at national and international level, combined to the degree of empowerment of its members, evidence of joint work and integration ration of thematic networks of collaboration.