Effective Internal Friction Angle Research Articles

A quantitative study of the effects of physical properties and external loads on the liquefaction of saturated sand based on an intelligent numerical cyclic triaxial test system

ABSTRACT Soil liquefaction would cause significant damage to the safety of cargo transportation. The aim of this article is to conduct a quantitative study of the influence of the main physical characteristic parameters of saturated sand and external loads on its liquefaction. On the basis of the physical cyclic triaxial test (CTT), the finite element simulation model and PSO-BP neural network prediction model and importance analysis model were optimised in this study. Based on this, an innovative intelligent numerical CTT system for saturated sand was constructed. The research results indicate the influence of external load, effective internal friction Angle and plasticity index on the liquefaction of saturated sand is significant, and the average weight is 40.15%, 29.15% and 25.05%, respectively. In this paper, the relevant research provides a theoretical basis for effective control of sand liquefaction and provides new ideas and feasible solutions for subsequent research on sand liquefaction.

Time-dependent probabilistic evaluation of rainstorm-induced shallow landslides considering influence of impermeable bedrock

ABSTRACT A time-dependent probabilistic evaluation method is proposed for assessing the stability of soil slopes during rainstorm events. The method considers multiple failure scenarios, including sliding along the wetting front and shallow soil–rock interface. The application of the method is demonstrated by a typical rainstorm-induced shallow landslide in Zhejiang Province, China. The results indicate that the landslides occurred when the failure probability exceeded a certain level, providing references for real-time landslide warnings. Moreover, the factors influencing the probabilistic results have been investigated. A two-dimensional limit state surface is used to explain the change of slope failure scenarios during the rainfall process, confirming the controlling role of the impermeable bedrock surface. The probabilistic evaluation results using the actual rainfall data can better reflect slope performance via comparing the computed failure probability using idealised rainfall patterns and actual rainfall data. Additionally, the parameter sensitivity analysis shows that the matric suction, the effective cohesion and the effective internal friction angle significantly influence the slope performance during the early stage of rainfall. However, during the later stage of rainfall, the saturated permeability coefficient becomes the most sensitive parameter. The applicability of the proposed method was further verified via three other typical rainstorm-induced shallow landslide cases.

Effect of gradation and relative density on shear strength of coral sand

ABSTRACT Due to the wide particle size distribution of coral sand, There are significant differences in mechanical behaviour of coral sand with different particle size distribution. It is of great significance to propose a quantitative analysis method for mechanical properties considering the effect of gradation. In this study, 27 groups of coral sand specimens with particle size ranging from 5 mm to 0.125 mm were prepared. The consolidated undrained (CU) triaxial shear tests were carried out and the influence of gradation and relative density on the shear characteristic were discussed. The grading and relative density of coral sand are controlled by the median particle size (d50) and relative density (Dr), The results show that the peak deviator stress decreased, and the effective internal friction angle first increased and then decreased with the increase of d 50. Both the peak deviator stress and effective internal friction angle of coral sand increase with the relative density. A parabolic relationship was founded between the effect internal friction and d 50 as D r was constant. The effective friction angle peaked when d 50 was 2 mm. Finally, a calculation method of shear strength parameter considering the gradation and relative density of coral sand was proposed.

Estimation of Effective Internal Friction Angle by Ball Penetration Test: Large-Deformation Analyses

Estimation of Effective Internal Friction Angle by Ball Penetration Test: Large-Deformation Analyses

Shear strength model of unsaturated frozen soil based on soil freezing characteristic and soil water characteristic

The strength characteristics of unsaturated soil after freezing significantly influence the safety of engineering construction in frozen soil regions. In this study, the soil freezing characteristic curve (SFCC) and soil water characteristic curve (SWCC) of unsaturated lean clay were tested. Based on the similarity between SFCC and SWCC, the unfrozen water content of SFCC was used to replace the water content of the SWCC to obtain the expression for soil suction under different negative temperatures. A shear strength model of unsaturated frozen soil was established. According to unsaturated triaxial tests under different conditions, the effectiveness of the established unsaturated soil shear strength model was verified. The test results show that in the rapid freezing stage of the SFCC, the volumetric unfrozen water content with an initial matrix suction of 57 kPa exhibited the largest rate of change. The stress-strain curve of soil at positive temperature is strain hardening type, and that at negative temperature presents different types under the influence of temperature, initial matrix suction and confining pressure. The effective cohesion and internal friction angle of soil varied significantly under the influence of temperature and initial matrix suction. When the initial matrix suction was constant, the unsaturated shear strength of the soil increased nonlinearly with a decrease in temperature. When the temperature was ≥−5 °C, the shear strength increased with an increase in initial matrix suction, but decreased when the temperature was ≤−5 °C. The model fitting results were consistent with the measured results of the unsaturated triaxial test, which verifies the validity of the model. This research can provide a reference for studying the mechanical characteristics of unsaturated frozen soil under negative temperature.

Multiple Parameters Determination Method of Hardening Soil Model Based on Particle Swarm Optimization

The utilization of numerical analytic techniques has become essential in evaluating the environmental consequences of excavation in foundation pits. The careful selection of suitable soil constitutive models has significant importance in this regard. The Hardening Soil (HS) model has become widely utilized in the numerical analysis of foundation pits among the several models considered. The essence of a constitutive model is in the identification and determination of its calculation parameters. The stress–strain curve is derived by conducting triaxial testing, utilizing the inherent properties of the particle swarm optimization (PSO) technique. The objective function entails quantifying the disparity between stress–strain curves obtained from various parameters and experimental curves while iteratively searching for five crucial parameters of soil‐hardening models: effective internal friction angle φ, effective cohesion, failure ratio Rf, stiffness level‐dependent power exponent, and standard triaxial‐drained test secant stiffness . The objective of this research is to create a computational software utilizing the Python programming language to execute PSO with the purpose of determining sets of five fundamental soil constitutive parameters. This research employs optimized parameters acquired from PSO to construct a numerical model for foundation pits and performs numerical computations. Accurate findings may be reached by comparing the measured deformation in the numerical simulation with that seen in actual foundation pits. The results demonstrate a high degree of consistency between the experimental curves and the five parameter combinations obtained through the PSO algorithm, with an error rate not exceeding 8.2%. Moreover, the optimized curves exhibit closer alignment with theoretical expectations. The settlement values calculated using a numerical model based on optimized parameters show only a 6.12% deviation from actual measurements while closely following the trend of the observed curve. This outcome has the potential to greatly alleviate the burden of conducting indoor tests and holds considerable practical value in engineering applications. The observable optimization impact of PSO also serves as evidence of its viability in improving soil constitutive parameters, providing new perspectives and sources of information for future progress in this domain.

An Attempt to Predict the Effective Angle of Internal Friction for Remolded Clayey Soils Using the Vane Shear Test: Some Important Implications

An Attempt to Predict the Effective Angle of Internal Friction for Remolded Clayey Soils Using the Vane Shear Test: Some Important Implications

Stability analysis of a slope containing water-sensitive mudstone considering different rainfall conditions at an open-pit mine

Mudstone, as a typical soft rock with wide distribution, has been endangering the slopes containing mudstone by its water-sensitivity of swelling and weakening strength when encountering water. To comprehensively understand the water-sensitivity of mudstone and reveal its influence on slope stability, we took the working slope containing water-sensitive mudstone of Shengli No.1 open-pit coal mine in Xilinhot, Inner Mongolia, China, as an example. Mudstone samples taken from the working slope were remodeled and saturated, and then triaxial tested to obtain the effective cohesion and effective internal friction angle. The filter paper method was used to obtain the soil–water characteristic curve of unsaturated mudstone. The pore structure of mudstone samples with different water contents were analyzed using the mercury intrusion porosimetry tests combined with the fractal dimension. The total pore content of the mudstone sample with lower water content is greater than that of the mudstone sample with higher water content. The mesopores are more in the mudstone sample with lower water content, while the small pores are more in the mudstone sample with higher water content. The variation of water content will change the complexity of mudstone pore structure. The higher the water content, the simpler the mudstone pore structure and the smoother the pore surface. Numerical calculations were conducted on the stability of the working slope under different rainfall conditions. The effective saturation on the mudstone layer surface changed and the plastic strain all occurred on the mudstone steps under different rainfall conditions. The key to preventing landslide of the slope containing water-sensitive mudstone in Shengli No.1 open-pit coal mine is to control the deformation and sliding of the mudstone layer.

Study on the Characteristics of Effective Internal Friction Angles of Silty Clay from the Yellow River Delta and the Inverse Method of CPTu Testing

This study focuses on the silty clay of the Yellow River Delta, conducting laboratory experiments to explore the strength characteristics of typical silty clay in the Yellow River Delta. The study utilizes CPTu calibration chamber tests to systematically reveal the features of cone tip resistance (qt), side friction resistance (fs), and pore water pressure (u2) of the silty clay. This research provides a theoretical basis for Delta investigation in the Yellow River region. The study compares the applicability of existing CPTu inversion methods and highlights the NTH method’s advantages in evaluating silty clay’s effective internal friction angle. Supported by indoor calibration chamber tests, the study confirms the reliability of the NTH method in estimating the effective internal friction angle under normally consolidated conditions while also identifying its limitations. These research findings offer data support for the in situ rapid and accurate estimation of design parameters, like the internal friction angle and undrained shear strength of the silty clay in the Yellow River Delta. Moreover, they provide insights for obtaining other crucial in situ data.

Analytical Solution for Bearing Capacity of Reinforced Strip Footings on Unsaturated Soils under Steady Flow

The study of analytical solutions for the bearing capacity of reinforced soil foundations is a very important topic in engineering mathematics. Existing evaluations of the foundation-bearing capacity on reinforced soils are based on dry conditions, while many foundations are located on unsaturated soils in real engineering. In this paper, a new formula for the bearing capacity of reinforced strip footings on unsaturated soils is presented. Two sliding failure mechanisms are constructed based on the position of the reinforcement layer relative to the sliding surface. The distribution of apparent cohesion in the depth direction is calculated by considering the effect of matrix suction. By additionally considering the work conducted by the reinforcement and the contribution of the apparent cohesion, the bearing capacity formula is obtained using the upper bound theorem of limit analysis. The bearing capacity solution is obtained by adopting the sequential quadratic programming (SQP) algorithm. Comparing the results under two failure mechanisms, the optimal bearing capacity and the optimal embedment depth of reinforcement are obtained. The results of this paper are consistent with those of the existing literature. Finally, the effects of reinforcement embedment depth, effective internal friction angle, uniform load, and unsaturated soil parameters on the optimal bearing capacity are investigated through parametric analysis. This paper provides useful recommendations for the engineering application of reinforced strip footings on unsaturated soils.

Comprehensive powder flow characterization with reduced testing

Powder flow is a critical attribute of pharmaceutical blends to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties. This study aims at characterizing different powder blends with a number of different rheologic techniques, in order to understand how particles’ attributes and interaction between components within the formulation generate different responses when analysed by different rheological tests. Furthermore, this study intends on reducing the number of tests in early development phases, by selecting the ones that provide the best information about the flowability attributes of the pharmaceutical blends. This work considered two cohesive powders - spray-dried hydroxypropyl cellulose (SD HPMC) and micronized indomethacin (IND) – formulated with other four commonly used excipients [(lactose monohydrated (LAC), microcrystalline cellulose (MCC), magnesium stearate (MgSt) and colloidal silica (CS)]. The experimental results showed that powder flowability may be affected by materials particles’ size, bulk density, morphology, and interactions with lubricant. In detail, parameters, such as angle of repose (AoR), compressibility percentage (CPS), and flow function coefficient (ffc) have shown to be highly affected by the particle size of the materials present in the blends. On the other hand, the Specific Energy (SE) and the effective angle of internal friction (φe) showed to be more related with particle morphology and materials interaction with the lubricant. Since both ffc and φe parameters are generated from the yield locus test, data suggest that a number of different powder flow features may be understood only by applying this test, avoiding redundant powder flow characterization, as well as extensive time and material spent in early development formulation stages.

Deformation analysis of underwater shield tunnelling based on HSS model parameter obtained by the Bayesian approach

Deformation analysis and control of underwater large-diameter shield tunnels is a prerequisite for safe tunnel construction. Reasonable selection of constitutive model and its parameters is the key to accurately predicting the deformation induced by underwater shield tunnelling. In this paper, the finite element analysis of cavity expansion during the piezocone penetration test (CPTU) based on the hardening soil model with small strain stiffness (HSS) model was carried out, and the correlation model of the normalized cone tip resistance Q with the reference secant modulus E50ref and the effective internal friction angle φ’ was established and verified using mini CPTU chamber test. Then, a Bayesian probability characterization approach for E50ref of silty clay based on CPTU was proposed. Furthermore, the deformation analysis of Jinan Yellow River tunnel crossing the south embankment was carried out to verify the reliability of the proposed approach. The good agreement between the field measurement and numerical simulation confirms that the parameters obtained by the Bayesian approach are reliable. Finally, a sensitivity analysis was performed to study the law of riverbed settlement induced by underwater large-diameter shield tunnelling. The results show that the increasing support pressure could effectively reduce the riverbed settlement, but there is an upper limit. The optimal support pressure of established model is between 0.45 MPa and 0.5 MPa. The uphill section causes greater riverbed settlement than the downhill section. Under the same condition, increasing buried depth and water level will lead to a more significant settlement.

Investigating the compressibility and flowability of cocoa powders: A solution for chocolate industry

AbstractThe flowability and compressibility properties were determined for two types of cocoa powders, which are used commercially in chocolate industries; alkalized and natural cocoa powders. Physical and flow properties have a very significant role in the flow behavior, which relates to the handling, transportation, and storage of bulk powders. Throughout the research, it was observed that the properties of both cocoa powders are similar. The objectives of this work are to compare the compressibility and flowability between alkalized and natural cocoa powders and to design the minimum opening size of hopper for mass flow based on their flow properties. Jenike's mathematical methodology is applied during the research for the design of conical hoppers for mass flow. Besides, powder flow analysis using powder flow analyzer is one of the testing methodologies in this research. In addition, direct shear box tests were performed with three different normal stresses. The alkalized cocoa powder needs 1.366 m in diameter for the opening of the hopper, while the natural cocoa powder needs 1.531 m. From the results of the study conducted, it was concluded that both cocoa powders are very cohesive and have poor flow properties. This research reveals that the physical and flow properties of two main types of cocoa powder contributed a lot to the process of hopper design, enhance process understanding, and also applicable for analyzing the powder behavior at any stage in industry.Practical applicationsCocoa powder is the essential ingredient of chocolate manufacturing and other food industry having a chocolate‐like flavor including beverages, biscuits, desserts, and so forth. In chocolate industry, the flow behavior of cocoa powders can affect manufacturing efficiency, which directly affects the production capacity and product quality in terms of its weight and content uniformity. In this study, the critical design parameters such as hopper angle and size of opening were determined to improve the flowability of cocoa powders when passes through hopper. The findings of the present study make it possible for an accurate estimation of a correct intersection with the hopper flow factor line and effective angle of internal friction (δ), extrapolating the powder flow function ff curve to obtain hopper opening size for each cocoa powder for better flowability.

Experimental study on soil-water characteristics and strength characteristics of complete-intense weathering mudstone in seasonal frozen area.

To study the soil-water characteristics and shear strength of unsaturated complete-intense weathering mudstone, the soil-water characteristic curve of complete-intense weathering mudstone and the matric suction of mudstone samples under natural state were measured. This measurement was through a soil-water characteristic test using a pressure plate instrument. Based on the results of soil-water characteristic test, an unsaturated (saturated) triaxial shear test was carried out. Under different temperatures and confining pressure conditions, the shear strength and deformation characteristics of complete-intense weathering mudstone under natural water content and saturation conditions were investigated. The results show that the percentage of silt and clay in unsaturated complete-intense weathering mudstone in natural state is relatively high, with the mudstone having less sand, and a weak permeability and exhibiting a significant capillary phenomenon. The complete-intense weathering mudstone with a natural moisture content of 19.15% has a matric suction of 210 kPa. When the temperature is constant, the shear stress of the sample increases with the increase of confining pressure. When the temperature decreases from 0 to -20°C, the influence of confining pressure on the rock samples gradually decreases. The rock sample has the property of strain hardening during shearing. Under the same matric suction, the total cohesion increases with the decrease of temperature. At a positive temperature, the effective internal friction angle increases with the decrease of temperature. At a negative temperature, the lower the temperature, the smaller the effective internal friction angle. The test of shear strength parameters of saturated complete-intense weathering mudstone is simple and conservative. In practical engineering, the basic properties of unsaturated complete-intense weathering mudstone can be predicted by testing the shear strength parameters of saturated complete-intense weathering mudstone. The results of the study are important for better understanding the nature of unsaturated complete-intense weathering mudstone and improving the safety of engineering construction in complete-intense weathering mudstone areas.

Stability Analysis of Box Tunnel Working Face under Non-Uniform Support Pressure

For rectangular section tunnel construction, soil bin pressure fluctuates under biaxial emergence conditions. Support pressure is difficult to uniformly distribute, and it can easily cause instability of the tunneling face. The Silo-wedge model is used to perform horizontal strip splitting of parts of the soil at risk for instability under unsupported conditions. In the ultimate equilibrium analysis, the strength discounting method is introduced, a new expression for the safety factor is derived by combining the horizontal strip splitting equilibrium equations, and the safety factor is solved numerically. When the opening range is greater than 0.75 and the effective internal friction angle of the soil is less than 25°, the safety coefficient is less than 1, and destabilization damage is likely to occur. The field application of a box tunnel project in Suzhou demonstrates that the research results have good engineering applicability to the issue.

Mechanical and Chemical Behaviour of Water Treatment Sludge and Soft Soil Mixtures for Liner Production

Background: Clay-based and geosynthetic liners are generally used as hydraulic barriers in solid waste disposal facilities, mining tailing ponds, and soil-based wastewater treatment technologies, avoiding the leaching of hazardous compounds into subsoil and groundwater. Water treatment sludge (WTS) is a water treatment plant (WTP) residue which due to hydraulic properties seems to decrease the permeability in WTS:soil mixtures and may become an alternative material to produce sustainable waste-based liners. Objectives: This research aims to characterize and analyse physical, chemical and mechanical parameters of a WTS, a soft soil and four mixtures WTS:soil following 05:95%, 10:90%, 15:85%, 20:80% ratios, Thereby, evaluating the best ratio for producing waste-based liners for civil engineering applications. Methods: The geotechnical characterization was performed for particle size distribution, specific surface, specific gravity, Atterberg limits, and Normal Proctor compaction; chemical composition due to oxides analyses through X-ray fluorescence (XRF), mineralogical description by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) coupled for imaging; and mechanical behavior performing - –oedometric consolidation, consolidated undrained (CU) triaxial, and falling head permeability. Tests were conducted for all mixtures, the soil, and WTS, with pointed-out exceptions. Results and Discussion: The results showed that the fine-grained WTS filled the soil voids but rearranged soil particles, thus, compacted dry unit weight decreased with WTS addition, probably due to its chemical composition with high amounts of aluminium and silica. The compressibility of the compacted mixtures did not differ significantly compared to the soil, while the shear strength analysis demonstrated a reduction in cohesion and an increase in the effective internal friction angle proportional to WTS addition. Hydraulic conductivity increased with WTS until 10% of residue introduction, decreased for 15%, and continued to decrease for 20%, reaching optimum permeability at 15%. Conclusion: The incorporation of WTS can improve or just not interfere with soil’s properties to be used as liner material in solid wastes storage facilities, mining ponds and soil-based wastewater treatment technologies. Furthermore, 15% of WTS (15:85% mixture) incorporation provided the best results meeting the hydraulic conductivity requirement for liner materials, i.e., equal, or lower than 10-9 m/s. The reuse of WTS for this purpose would allow producing a new added-value material in the scope of circular economy.

Experimental Study on the Effects of Matric Suction on Shear Properties of Polypropylene Fiber Reinforced Unsaturated Clay.

Matric suction has an important effect on the behavior of unsaturated soils, and polypropylene fibers are often used to improve soil. In order to probe into the mechanism of matric suction and fiber reinforcement, triaxial shear tests are carried out with changing matric suction and net confining pressure. Unsaturated clay in the Shaoxing section of East Zhejiang Grand Canal is selected with polypropylene fiber as a reinforcement material in the tests. The results show that the total cohesion intercept and effective internal friction angle of soil increase with the increase in matric suction, while the adsorption internal friction angle decreases gradually. Similarly, the contribution of matric suction to shear strength decreases. The total cohesion intercept is more sensitive to matric suction. As the length of fiber is 12 mm, the shear strength parameters of soil will be improved accordingly, which makes the fiber reinforcement achieve the best. The stress-strain relationship is approximately hyperbolic and strain hardening. The characteristics of strain hardening are more obvious with the increase in matric suction, and the soil specimens present plastic failure. The volumetric strain of specimen is more sensitive to the changing net confining pressure. It increases with the increase in net confining pressure, and increases linearly as the matric suction is zero. The failure modes of triaxial tests are divided into tensile failure and friction failure.

Secondary Grouting Pressure Limit of Shield Tunnels in Loess Strata Based on Bolt Shear Behavior

A loess stratum was selected as the research object, assuming that the slurry diffuses in a hemispherical shape during secondary grouting. Based on the unified strength theory describing the failure characteristics of loess and the critical condition of bolt shear failure, the critical pressure value of the secondary grouting in loess strata was determined theoretically. The reliability of the theoretical analysis was verified by the numerical modeling realizing the large deformation of formation and the dynamic injection of slurry. The critical grouting pressure of 821.80 kPa of theoretical calculation was obtained. Comparing the results of the numerical simulation analysis, it was found that the critical grouting pressure calculated using the theoretical equation had a safety index of 1.14. Bounded by βu (the ratio of expansion radius RP of soil plastic zone to the expansion radius Ru of the slurry) equal to 2.65, the water pressure at the grouting port is the main factor affecting the upper limit of critical grouting pressure when it is less than 2.65, and the effective internal friction angle of soil layer is the main factor when it is greater than 2.65. The influence of matric suction on the upper limit of the critical grouting pressure can be ignored.

Experimental Investigation of Consolidated Undrained Shear Behavior on Peaty Soil in Dian-Chi, China

Peat deposits are extensively distributed worldwide, and the various common engineering-failure problems involving peat have attracted greater attention from researchers in regard to understanding the mechanical behavior of peat. This study investigated extensive index and consolidated undrained triaxial compression tests applied to the peaty soils of Dian-Chi Lake, located in Yunnan, China. A series of consolidated undrained triaxial compression tests on peat specimens were carried out in this study, and the influences of confining pressure, organic matter content and strength parameters were investigated. The test results indicate that, to obtain a B-value greater than 0.98, the average back pressure of the Dian-Chi Lake peaty soil should be at least 150 kPa, with organic matter contents N ranging from 30% to 85%. Compared with the existing oedometer consolidation results of the research team, the values of compressibility and permeability behavior under the oedometer and isotropic consolidation conditions are not significantly different. In addition, the average failure strain, εf, ranged from 9% to 15% for the investigated normally consolidated specimens, and the average effective angle of internal friction was 43.8°, which is greater than the maximum internal friction angle of 35° for typical soft clay and silt soils. A correlation was proposed by curve fitting the experimental data to better capture the nonlinear relationship between φ′ and N. Furthermore, the values of the normalized undrained strength, Su/σc′, varied from 0.56 to 0.84, which is larger than that of the inorganic soft clay and silt deposits.

Development law and growth model of dynamic pore water pressure of tailings under different consolidation conditions.

Tailings dams are in danger of liquefaction during earthquakes. The liquefaction process can be indirectly reflected by the evolution rule of the dynamic pore water pressure. To study the development law of dynamic pore water pressure of tailing sand under different consolidation conditions, the evolution equation of critical dynamic pore water pressure of tailings under isotropic and anisotropic consolidation conditions was derived based on the limit equilibrium theory. Moreover, the development law of dynamic pore water pressure was expounded theoretically. The dynamic triaxial tests of tailing silty sand and tailing silt under different dry densities, consolidation ratios, and confining pressures were performed. The dynamic pore water pressure ratio and vibration ratio curves of tailings under isotropic and anisotropic consolidation were analyzed, and a dynamic pore water pressure growth index model suitable for both isotropic and anisotropic consolidation was derived. The results showed that the critical dynamic pore water pressure was positively correlated with the confining pressure and average particle size of tailings under isotropic consolidation conditions. The tailings have a limit dynamic effective internal friction angle [Formula: see text] under the anisotropic consolidation condition. The evolution law of critical dynamic pore water pressure can be judged according to the dynamic effective internal friction angle of tailing sand φd and [Formula: see text] values. The consolidation ratio significantly affects the dynamic pore pressure growth curve while confining pressure and dry density do not. For different tailing materials, the dynamic pore water pressure ratio is positively correlated with tailing particles. The dynamic pore water pressure growth process of tailing silty sand and tailing silt can be divided into two stages: rapid and stable growths. The development law of two types of tailings can be described by the dynamic pore water pressure growth index model. The research results can provide a theoretical basis for the seismic design of tailings dams in practical engineering.