Horizontal Shear Stress Research Articles

Frost heave characteristics of subgrade silty clay affected by cyclic stress: Experiments and prediction model

To investigate the effects of traffic loads on frost heave behaviors, frost heave tests of silty clay soil were conducted using an improved temperature-controlled cyclic compression-shear device. This research employed three stress modes: vertical cyclic stress, horizontal cyclic shear stress, and complex cyclic stress that combines vertical cyclic stress with horizontal cyclic shear stress. Additionally, it considered the effects of the amplitude and frequency of complex cyclic stress. Test results show vertical cyclic stress densifies specimens and restrains vertical displacement development. Vertical cyclic stress's pumping effect promotes water absorption during frost heave. Horizontal cyclic shear stress can increase in-situ frost heave and induce minor consolidation than vertical cyclic stress, dramatically enhancing vertical displacement. Under complex cyclic stress conditions, vertical cyclic stress and horizontal cyclic shear stress at low amplitudes and frequencies enhance vertical displacement. The primary component that promotes the frost heave ratio is horizontal cyclic shear stress, which could lead to a looser frozen soil structure. Finally, an improved frost heave ratio prediction model was developed, considering the influences of vertical cyclic stress, horizontal cyclic shear stress, and loading frequency.

Equation for the simplified calculation of the horizontal shear stress in composite beams of rectangular cross-section with considerable width

The theory of elasticity allows describing the law of variation of shear stresses Τzy and Tzx for a beam of rectangular cross-section, however, the expressions are extensive and complex. For beams with a width/depth ratio equal to 0.25, it is allowed to calculate approximately the maximum shear stress Tzy, with the Collignon-Zhuravski equation. Depending on the width/depth ratio of the beam, it will depend on the percentage of error made. Unfortunately, for the shear stress Tzx there is no approximate formula available to determine the value of the shear stress. Using a simplified procedure, a differential beam element was analyzed in the elastic field for different width/depth ratios and a very simple expression was obtained. The results of the approximate formula were compared with the values obtained from the application of the exact formula and the results of a linear numerical analysis using the finite element method. For cross-sections of homogeneous beams and composite beams of considerable width, it is essential to determine the horizontal shear stresses Tzx in particular in the case of vertical planks, arranged side by side, connected solidly by horizontally arranged mechanical connectors, since the shear stresses Tzx developed across the width of the cross-section may considerably exceed the vertical shear stresses Tzy and furthermore govern the pattern, spacing and cross-section of the mechanical connectors. The validity of the approximate expression for calculating the maximum value of the shear stress Tzx was limited to beams with a width/depth ratio between 0.25 and 10.0.

Frost heave of subgrade soil under complex traffic loads: Test system and experiments

Soil moisture freezing in cold climates leads to frost heave, a phenomenon influenced by soil texture, temperature, moisture levels, and applied loads. This investigation explores frost heave characteristics of subgrade soil under traffic-induced cyclic stresses, including cyclic compressive stress and alternating horizontal cyclic shear stress. A new frost heave test system was developed, featuring advanced temperature control and accurate loading path reproduction. Comprehensive frost heave experiments were performed to examine the frost heave process under various cyclic stress circumstances. Results indicate that cyclic stresses intensify in-situ frost heave of soil, with horizontal cyclic shear stress having a more significant promoting effect than vertical cyclic stress. The combination of vertical cyclic stress and horizontal cyclic shear stress leads to an increase in segregated frost heave. Moreover, vertical cyclic stress amplifies water absorption during soil frost heave. Total vertical deformation encompasses frost deformation in the frozen zone and consolidation in the unfrozen zone. Vertical cyclic stress may inhibit segregated ice lens formation and encourage consolidation in the unfrozen zone, thereby impeding vertical deformation. The simultaneous application of vertical cyclic stress and horizontal cyclic shear stress results in more intense ice segregation and moisture accumulation near the stable frost front.

Impact of shear stress on sacral pressure injury from table rotation during laparoscopic colorectal surgery performed in the lithotomy position

This study aimed to evaluate the impact of shear stress on surgery-related sacral pressure injury (PI) after laparoscopic colorectal surgery performed in the lithotomy position. We included 37 patients who underwent this procedure between November 2021 and October 2022. The primary outcome was average horizontal shear stress caused by the rotation of the operating table during the operation, and the secondary outcome was interface pressure over time. Sensors were used to measure shear stress and interface pressure in the sacral region. Patients were divided into two groups according to the presence or absence of PI. PI had an incidence of 32.4%, and the primary outcome, average horizontal shear stress, was significantly higher in the PI group than in the no-PI group. The interface pressure increased over time in both groups. At 120 min, the interface pressure was two times higher in the PI group than in the no-PI group (PI group, 221.5 mmHg; no-PI group, 86.0 mmHg; p < 0.01). This study suggested that shear stress resulting from rotation of the operating table in the sacral region by laparoscopic colorectal surgery performed in the lithotomy position is the cause of PI. These results should contribute to the prevention of PI.

A shear stress parametrization for arbitrary wind farms in conventionally neutral boundary layers

In the context of large off-shore wind farms, power production is influenced greatly by the turbine array's interaction with the atmospheric boundary layer. One of the most influencing manifestations of such complex interaction is the increased level of shear stress observed within the farm. This leads to higher momentum fluxes that affect the wind speed at the turbine locations and in the cluster wake. At the wind farm entrance, an internal boundary layer (IBL) grows due to the change in effective roughness imposed by the wind turbines, and for large enough clusters, this can reach the unperturbed boundary layer height in what is referred to as the fully developed regime. Downwind, a second IBL starts growing, while the shear stress profile decays exponentially to its unperturbed state. In the present study, we propose a simple analytical model for the vertical profile of the horizontal shear stress components in the three regions identified above. The model builds upon the top-down model of Meneveau (J. Turbul., vol. 13, 2012, N7), and assumes that the flow develops in a conventionally neutral boundary layer. The proposed parametrization is verified successfully against large-eddy simulations, demonstrating its ability to capture the vertical profile of horizontal shear stress, and its evolution both inside and downwind of the wind farm. Our findings suggest that the developed model can prove extremely useful to enhance the physical grounds on which new classes of coupled wind farm engineering models are based, leading to a better estimation of meso-scale phenomena affecting the power production of large turbine arrays.

Evaluation of the horizontal cyclic shear stress on the enclosed soil in DSM grid-improved ground by numerical simulation

Deep soil mixing (DSM) grids are widely used as effective countermeasures against liquefaction hazards. A simplified two-dimensional, nonlinear, finite element model involving DSM grid-improved ground is proposed to investigate the shear stress responses of the enclosed soil. A numerical model with several approximations of longitudinal walls was carefully validated by a centrifuge model test. The waist-shaped depth distribution of the horizontal cyclic shear stress acting on the enclosed soil (i.e., the “waist effect”) was revealed and well explained according to the characteristics of dynamic soil-grid interactions. Attention should be given to the increasing shear load sustained by the underlain layer, which may lead to an unexpected failure. A mathematical model for the shear stress reduction ratio was proposed based on a comprehensive numerical parametric analysis considering varying geometry and shear modulus of the DSM grid with a reasonable range. The proposed evaluation method, along with conventional liquefaction-triggering analysis, can be utilized for the seismic design of DSM grids in liquefaction mitigation. The previous design methods without considering the “waist effect” underestimate the overall horizontal cyclic shear stress acting on enclosed soil.

Nonlinear description of active earth pressure for finite backfill based on principal stress trajectory method subjected to steady unsaturated seepage

To simplify calculations, soil cohesion, horizontal shear stress, and unsaturated properties have usually been neglected in previous earth pressure analytical methods. This negligence has certain theoretical flaws and does not conform to the actual situation. Especially for finite backfill, which often occurs, it is worth continuing to expand research in this field to seek a more rigorous solution. This work presents an analytical framework for estimating the active earth pressure of finite backfill on inclined retaining walls under steady unsaturated seepage conditions. The extended Mohr–Coulomb failure criterion expresses soil shear strength, and a unified effective stress method considering the suction stress is adopted. For a classic failure model, a calculation method using curved differential elements is established based on the principal stress trajectory. The proposed method fully considers soil cohesion, arching effect, and unsaturated properties. Relative to the existing test and theoretical results, the rationality of this method is verified. The sensitivities of relevant parameters are discussed based on different assumed soil types. The results show that seepage significantly affects the lateral earth pressure. The earth pressure distributions vary greatly under different unsaturated types for various soils. The results can provide a reference for the selection of engineering backfill.

Lithospheric Stress Due to Mantle Convection and Mantle Plume over East Africa from GOCE and Seismic Data

The Afar and Ethiopian plateaus are in a dynamic uplift due to the mantle plume, therefore, considering the plume effect is necessary for any geophysical investigation including the estimation of lithospheric stress in this area. The Earth gravity models of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and lithospheric structure models can be applied to estimate the stress tensor inside the Ethiopian lithosphere. To do so, the boundary-value problem of elasticity is solved to derive a general solution for the displacement field in a thin elastic spherical shell representing the lithosphere. After that, general solutions for the elements of the strain tensor are derived from the displacement field, and finally the stress tensor from the strain tensor. The horizontal shear stresses due to mantle convection and the vertical stress due to the mantle plume are taken as the lower boundary value at the base of the lithosphere, and no stress at the upper boundary value of the lithospheric shell. The stress tensor and maximum stress directions are computed at the Moho boundary in three scenarios: considering horizontal shear stresses due to mantle convection, vertical stresses due to mantle plume, and their combination. The estimated maximum horizontal shear stresses’ locations are consistent with tectonics and seismic activities in the study area. In addition, the maximum shear stress directions are highly correlated with the World Stress Map 2016, especially when the effect of the mantle plume is solely considered, indicating the stress in the study area mainly comes from the plume.

Experimental and Numerical Study on Response Characteristics of Airport Pavement Subjected to Wetting in Silt Subgrade

Silt is often selected as the filling soil in Northwest and North China. “Pot cover effect” or rainfall infiltration are easily to cause localized wetting during the service period of airport. The response characteristics of pavement derived from aircraft loading under wetting condition are the basis to explore the evolution law of pavement damage. To investigate this response characteristics for different parameters of pavement under wetting condition, a self-developed model test system was developed, and the verified numerical model was then established. The interaction mechanisms of pavement slabs, and the influence of wetting on mechanical response in loading area of pavement under different pavement parameters were analyzed. The results showed that the increased vertical deformation depends on water-holding capacity of silt, and the vertical deformation under loading is little affected by pavement parameters. The peak shear stress and the increased peak shear stress derived from wetting at the bottom of pavement layers are largely influenced by elastic modulus of base course. For cement concrete pavement, the increase in load transfer capacity of joints cannot decrease the increase of peak stress, including horizontal stress and shear stress, derived from wetting. The increase in load transfer capacity of joints can decrease the stress concentration in surface layer, while the elastic modulus of surface layer has little influence. For bituminous pavement, optimal parameters of base course can be obtained to decrease the peak stress and the increase of peak stress derived from wetting in subgrade. The research can provide technical basis for the structure design, optimization, and disease treatment of pavement in airport engineering.

Seismic response of nuclear power station with disconnected pile-raft foundation using dynamic centrifuge tests

The typical foundation type for a nuclear power station is the raft foundation in rock areas. With the power demand, it is possible that a nuclear power station located in soft soil areas. Traditional connected pile raft foundation (CPRF) has been successfully used in soft soil areas. However, under earthquake loads, high horizontal shear stresses and bending moments are generated in the pile head. Accordingly, researchers have sought to develop an innovative disconnected pile raft foundation (DPRF), and the benefits of DPRF have simulated increasing researches on it in the last two decades. In this study, a series of dynamic centrifuge tests were carried out to identify the effect of cushion and its thickness on the dynamic characteristics of the nuclear power station with DPRF. A withe noise excitation and three earthquake waves with different seismic intensities were adopted as ground motion. The seismic responses of soil, structure, and bending moment of piles were analysed. A cushion thickness equal to the diameter of piles is recommended. Comparing with the CPRF, the cushion layer of DPRF has an isolation benefit. With the gravel cushion, attention must be paid to the horizontal displacement, inclination and rocking of the superstructure.

Earth pressure in narrow cohesive-fictional soils behind retaining walls rotated about the top: An analytical approach

There is currently a lack of an available design approach to estimate the earth pressure in narrow backfills behind retaining walls rotated about the top (RT). The considerations of some significant factors, primarily load transfer mechanisms (soil arching effect and horizontal shear stress in soils), failure mechanisms (shape and number of slip surfaces) and soil cohesion are often neglected for brevity in routine design. Such simplifications may lead to significant deviations from reality. This paper first uses the finite element limit analysis (FELA) technique to identify the underlying failure mechanisms and load transfer mechanisms. The results observed in FELA models indicate that active rotation of walls about the top develops one curved slip surface, which can be approximated by the log-spiral function. Under the soil arching effect, the upper intermediate passive zone with major principal stress rotation trajectory and the lower active zone with minor one can be defined. The arched differential element method (ADEM) is then introduced to formulate the earth pressure calculation. The results from newly published tests, existing analytical approaches, and FELA are compared to validate the accuracy of the proposed approach in both purely-frictional and cohesive-frictional soils. Parametric studies are further conducted to thoroughly understand the earth pressure problems, considering the effects of sensitive design variables (e.g. aspect ratio, soil strength parameters, and wall-soil interface friction angle). The analytical approach presented here would be a great extension to the design guidelines for the retaining structures with narrow backfills.

In situ stress characteristics of the NE Sichuan basin based on acoustic emission test and imaging logging

This study presents the distribution rule of in situ stress in the northeast Sichuan basin and its relationship with fracture. Sixty-seven sets of core samples of 21 Wells from the terrigenous clastic rock formation (Shaximiao, Qianfoya, Xujiahe) and marine carbonate formation (Jialingjiang, Leikoupo, Feixianguan) in the northeast Sichuan basin were tested by acoustic emission experiment. The in situ stress variation with the depth was established and the corresponding regression analysis was done. The horizontal principal stress direction of terrigenous clastic rock formation and marine carbonate rock formation was obtained by combining the dual diameter data of 6 wells and the imaging logging data of 3 wells. The results show that the vertical stress in the northeast of Sichuan basin has a linear relationship with the depth, and there is little difference between the vertical stress and the overburden weight of rocks. The maximum and minimum horizontal principal stress and horizontal shear stress increase with the burial depth. The divergence degree of horizontal shear stress with depth greater than 3000 m is greater than that of the stratum smaller than 3000 m. The horizontal stress plays a dominant role in the northeast Sichuan basin. With the increase in depth, the influence of tectonic stress field decreases and the vertical stress increases. Impacted by Dabashan and Qinling plate tectonic movement, the direction of in situ stress in marine carbonate strata is nearly east–west. The direction of maximum horizontal principal stress in terrigenous clastic rock formation is basically northwest–southeast. The imaging logging data show that the fracture direction is consistent with the horizontal principal stress direction, and the present in situ stress direction is favorable to the secondary reconstruction of natural fractures, and the fractures keep good opening. The distribution law of in situ stress in northeast Sichuan basin shows σH > σV > σh, indicating that the fault activity in this area is dominated by strike-slip type, the tectonic stress field is dominated by horizontal tectonic stress, in addition that the stress state is conducive to reverse fault activity.

Shearing stress of shoaling internal solitary waves over the slope

The interaction between internal solitary waves (ISWs) and the seabed has been extensively studied, so do the energy loss, sediment resuspension, parameterization criterion and near-bed pressure variation. However, the horizontal and vertical shearing stresses of ISWs have not been directly measured. In this paper, flume experiments were designed to examine the near-bed pressure variation of shoaling ISWs over the slope with a novel device possessing four pressure sensors in different directions. Then the vertical and horizontal shearing stresses of ISWs were analyzed, with the shearing stress of ISWs in the South China Sea predicted based on field observation. The results showed that the maximum pressure variation of shoaling ISWs approximated 20 Pa, with the ISWs' horizontal shearing stress, about 3–6 Pa and the vertical one, about 10 Pa. It was predicted that the horizontal and vertical shearing stresses of ISWs in the open ocean were 5–100 kPa, larger than the maximum critical shearing stress of the sediment. This paper could promote the understanding of the seabed damage caused by ISWs and is expected to provide a reference for future field experiment design for the direct interaction measurement between ISWs and seabed sediments.

Geomechanical stress conditions to induce half-moon events during hydraulic fracturing

Half-moon events are a special type of microseismic source mechanism that is found at various hydraulic-fracturing sites, but hardly observed in natural seismicity. This event type can be explained either by a vertical slip on a nearly vertical fault plane or by a horizontal slip on a nearly horizontal fault plane. For this, special stress conditions are required, for instance, nearly equal horizontal and vertical compressional stresses and significant shear stresses. Such conditions are created during hydraulic stimulation as shown by our numerical simulations. By applying fracture pressure to the surface of the hydraulic fracture, the stress field in the vicinity of the hydraulic fracture can locally rotate and horizontal or vertical faults become optimally oriented. We found that such rotations can occur in locations where the elastic properties of rocks change (i.e., the fracture crosses a layer interface) or at the tips of the hydraulic fracture. Depending on the stress regime, our model explains half-moon events generated by slip on nearly horizontal fault planes in strike-slip environments and by slip on nearly vertical fault planes in normal faulting tectonics. Moreover, our models explain several common characteristics observed in multiple case studies. This includes the observation of the high portion of half-moon events and opposed shear senses in different depths and on opposite sides of the fracture.

MATHEMATICAL ANALYSIS OF VISCOSITY AND REABSORPTION ON URINE FLOW THROUGH A STRAIGHT NARROW TUBE

This study investigates the effect of variable viscosity (exponential and linear) and constant reabsorption for the urine flow through a narrow tube. The inertial free flow of viscous fluid has been governed by the momentum and mass conservation through the cross-section of axisymmetric tube. The governing partial differential equations have been simplified with the help of stream function and stress components with exponential and linear variable viscosity. The resulting partial differential equations have been solved by the inverse method and give the explicit expressions for velocity, pressure, shear stress, flux and leakage of flow. It has been observed that flow in transverse direction increases with the increase in reabsorption velocity at wall, whereas horizontal flow, shear stress and volume flow rate become slow with the increase in uniform reabsorption velocity. Effect of viscosity is significant near the walls of tube because the axial velocity accelerates by increasing viscosity parameter due to the pressure gradient near the center of tube but it decelerates near the walls of tube due to surface friction. Also, the special case of variable viscosity is discussed by assuming the linear type of viscosity. The derived data for the velocity and flow rate have been used to measure the fractional reabsorption in proximal tube with varying viscosity near the wall.

Cyclic strength of loose anisotropically-consolidated calcareous sand under standing waves and assessment using the unified cyclic stress ratio

Progressive and standing waves can produce instability of the seabed and seabed-supported marine structures. In this paper, the stress paths induced by standing waves were deduced to provide a theoretical basis for laboratory element tests to establish the cyclic behavior of marine sediments, which can serve to improve the understanding of seabed liquefaction triggering and its consequences. The cyclic response of loose, isotropically- and anisotropically-consolidated (IC and AC, respectively) calcareous sand under the stress paths derived for standing waves was examined using hollow cylinder torsional shear (HCTS) tests. The stress paths corresponding to standing waves are a vertical line, horizontal line, and ellipse, in a coordinate system consisting of the axial stress difference and the horizontal shear stress, for a soil element located at the nodes, antinodes, and intermediate horizontal positions, respectively. The phase difference, θ, between axial stress difference and horizontal shear stress appears to range from −45° ~ 7° for wave and seabed characteristics representative of the North Sea. The ratio of axial stress difference and horizontal shear stress amplitudes, λ, varies in the real number field. The experimental results indicated that the failure modes of IC and AC specimens are cyclic mobility and residual deformation failure, respectively, irrespective of the stress paths imposed. With the same consolidation state and cyclic stress ratio, CSR, the number of cycles to failure, Nf, is strongly affected by θ and λ. The unified cyclic stress ratio, USR, is proposed to establish a single USR-Nf curve that can suitably describe the general cyclic strength of the calcareous sand specimens under different stress paths for a given consolidation stress ratio. The proposed USR enables estimation of the cyclic strength of IC and AC soils under complex stress paths based on the CSR-Nf curve obtained from conventional cyclic torsional shear or triaxial tests.

Experimental Study of Adobe Masonry and its Adherence with Reinforced Concrete Confinement Elements

The constructions with adobe masonry confined with concrete elements, experience a separation between them, mainly due to the inherent physical and chemical characteristics of both materials that are not very compatible with each other; adobe, a raw masonry with a high clay content, undergoes changes in its shape in the presence of humidity and temperature variation, which affects its adherence to concrete elements, compromising the confinement, function and stability of the walls. The different coefficients of expansion and contraction between concrete and adobe, added to their physical properties, make it difficult to achieve adequate adherence between these two materials. In the present study, 6 mixtures of earth (adobe) were designed, with different granulometry proportions to measure the adherence between adobe and concrete, identifying the most suitable one with the purpose of using it as a bonding material in walls for houses, from this study, with the best response being the sample MA-3. The test methodology was based on standards applicable to concrete and annealed brick masonry, as there is no available one for this material. Thirty-six adobe specimens adhered to concrete were tested, to which a normal load was gradually applied to their cross section, to a piece of adobe between two pieces of concrete, recording the ultimate horizontal shear stress between both materials. The scope is considered the result of the test of adobe pieces adhered to concrete subjected to horizontal shear force, considering different granulometry in the composition of the adobe mixture. This work provides a starting point for the standardization of the test and the justification of the need for an additional element that contributes to the confinement.

Analytical study on new types of shear connectors in composite slab

Profiled deck composite slab is gaining more popularity from the past two decades due to its easy, fast and economical construction. Shear connectors are a key element in the composite slab. It creates a tensile link between the steel sheet and Concrete and also transfers horizontal shear stresses from Concrete to deck sheet. The overall stiffness of the composite slab depends upon the shape of the profiled deck sheet as well as the type of shear connector utilized. In this research article, two new types of shear connectors named as S type and W type were proposed for profiled deck composite slab.The research comprises of non-linear finite element analysis using an effective constitutive model of the experimental four point bending test using ANSYS software. The behaviour of these new type of shear connectors are compared with conventionally used shear studs. The effectiveness of shear connectors in the composite system is analyzed by comparing it with a model without any shear connector. The behaviour of four composite slab models is analyzed based on deflection and slip characteristics. S-type and W-type shear connectors showed excellent behaviour compared to a conventionally sued shear connector and proved to be a better alternative solution.

Experimental Study on the Dynamic Modulus and Damping Ratio of Compacted Loess under Circular Dynamic Stress Paths

Dynamic loads such as earthquakes and traffic will simultaneously generate vertical dynamic stress and horizontal shear stress in the foundation soil. When the vertical dynamic stress amplitude is twice the horizontal shear dynamic stress amplitude, and the phase difference between them is 90°, a circular dynamic stress path is formed in the τzθd ~ (σzd − σθd)/2 stress coordinate system. To simulate the stress state of soil in the area of the circular dynamic stress path caused by bidirectional dynamic stress coupling, a series of tests of compacted loess under the action of a circular dynamic stress path were carried out using a hollow cylindrical torsion shear apparatus. The effects of the mean principal stress, dry density, and deviatoric stress ratio (the ratio of deviator stress to average principal stress) on the dynamic modulus and damping ratio of compacted loess were mainly studied. The test results show that, under the action of the circular dynamic stress path, the larger the mean principal stress is, the larger the dynamic compression modulus and dynamic shear modulus are. The dynamic compression modulus increases obviously with increasing dry density, but the dynamic shear modulus increases only slightly. When the deviator stress ratio increases from 0 to 0.4, the dynamic compression modulus and dynamic shear modulus increase to a certain extent. In addition, the greater the dry density and deviatoric stress ratio are, the greater the initial dynamic compression modulus and initial dynamic shear modulus of the compacted loess. The dynamic compression damping ratio of compacted loess increases with increasing mean principal stress, but the dynamic shear damping ratio decreases with increasing mean principal stress. Dry density basically has no effect on the dynamic compression damping ratio and dynamic shear damping ratio of compacted loess. When the dynamic strain exceeds 1%, the greater the deviatoric stress ratio is, the smaller the dynamic compression damping ratio and the dynamic shear damping ratio are. The research results can provide reference for the study of dynamic modulus and damping ratio of loess under special stress paths.

The Variation of the stress-and-strain state of the Vuoksi Fault Zone area (Vyborg district)

The stress-and-strain state of the rock massif and the kinematic type of faults of the Vuoksi fault zone (Karelian Isthmus) for the latest stage of tectonic history were determined by field tectonophysical methods. The main information was obtained from geological stress/strain indicators, which were mostly represented by measurements of minor faults and slickensides with kinematic information (the direction of relative displacement) on the fault plane. Near the Vuoksi fault zone, systems of faults with an orientation close to the strike of this regional fault structure are observed. Most widespread are strike-slip faults, whereas faults with normal or reverse displacement make up less than a quarter of the total number of faults. The STRESSgeol software based on the method of cataclastic analysis was used to restore stress-and-strain state. The variable orientation of the principal stress axes was determined in the studied area. The two main directions of maximum compression are NE-SW (to ENE-WSW) and NW-SE (to WNW-ESE). The axes of the maximum deviatory extension are subhorizontal and are directed in the NNE-SSW and NW (to WNW-ESE) direction. The intermediate axis often occupies a sub-vertical position. The horizontal shear stress state type prevails for the entire zone, and lateral shear displacements are also characteristic of this fault zone. This stress state type of the studied part of the Baltic Shield is significantly different from the stress state type of orogenic belts, where, along with horizontal shear stress state type, the situation of horizontal compression stress state type dominates. The obtained variability of the directions of maximum compression in the studied area can be preliminarily correlated with the previously identified zone of “unstable tectonic stresses” of the East European Platform.