Highway Soil Research Articles

On-site monitoring of expansive soil slope protected by soilbags based on the universal Beidou monitoring system

To explore an effective method for deformation monitoring and behavior prediction of expansive soil slope, field tests are conducted for a flexible slope protection scheme with soilbags that has been implemented in an expansive highway soil slope. A new monitoring system, i.e., the universal Beidou deformation monitoring system, is developed to overcome the limitations of traditional Global Navigation Satellite System (GNSS) software and hardware, simplify the hardware structure and realize the power sharing mode; furthermore, this system can create and upload a large amount of monitored data to a cloud platform to enable real-time calculation. Compared with traditional GNSS, the volume of equipment required is reduced by approximately 75%, and the cost is reduced by approximately 80%. Secondly, a multilevel safety early-warning evaluation system is constructed by integrating the monitoring results of the universal Beidou deformation monitoring system, bag damage states, rainfall conditions, and slope fissure development; additionally, a deformation early-warning mechanism of flexible support of soilbags was established. Finally, the deformation and collapse of flexible supports of soilbags can be successfully predicted in the field. This research on flexible support of soilbags provides new ideas and methods of deformation monitoring, safety evaluation, and early warning for expansive soil slopes.

Chemical and micronutrients assessment in Himalayan Foothill highway soil surface

This study examines the chemical properties and micronutrient concentrations of roadside soil in the ecologically sensitive Himalayan foothills of Uttarakhand, India. The primary objective is to assess soil contamination levels and their implications for urban ecosystem services. Soil samples from 13 locations were systematically collected, processed, and analyzed using atomic absorption spectrophotometry. Results indicated average concentrations of Zn, Cu, Fe, Mn, and Ni at 9.94, 3.28, 24.32, 17.35, and 0.28 mg/kg, respectively. Significant variations in soil chemical properties and micronutrient levels (p < 0.05) were observed across different sites, excluding phosphate levels. These findings underscore the critical need for targeted environmental management strategies to mitigate soil contamination and preserve vital ecosystem services in urbanized regions. The data provided can guide administrators in developing policies that promote sustainable development and environmental resilience.

Hydraulic Performance of Conventional and Conical Geotextile Units Filtering Two Highway Soils

Hydraulic Performance of Conventional and Conical Geotextile Units Filtering Two Highway Soils

A Study on Crushed Coconut Shells as Stabiliser to Soil

Road construction over soft subgrade soil is a major issue affecting cost and scheduling of highway projects. Many techniques have been conducted to strengthen the highway soil subgrade. One of them are using additives such as coconut shells, rice husk ash, stone dust, and fly ash. to strengthen the soil. The strength of the subgrade is commonly expressed as California Bearing Ratio (CBR). In this study, the crushed coconut shells (CCS) of 65 mm to 10 mm ranges of size was mix with the laterite soil. A series of unsoaked CBR test were conducted with an addition of 1, 2, 3, 4, 5, 6, 7 and 8% of CCS to determine the strength of the stabilized laterite soil. The laterite soil is classified as sandy SILT of high plasticity (MH) according to British Standard Classification System (BSCS). The results show that the CBR values of the stabilized soil increase with an increasing percentage the CCS. The stabilized soil with 4% CCS is the highest CBR value, 27.5%. The CBR% then decreasing as further additional of CCS %. The stabilised soil with an 8% CCS content had the lowest CBR value at 5.25%, which is lower than the unstabilised laterite soil’s CBR value. It is concluded that the additions of CCS have greatly improved the soil strength with the increment increase of CBR value. Hence CCS has a good potential for upgrading the CBR value of subgrade soil.

Machine-Learning-Based Road Soft Soil Foundation Treatment and Settlement Prediction Method

In order to effectively predict the settlement of soft soil foundation, improve the accuracy of road soft soil foundation settlement prediction, and improve the safety of the project, this paper proposes an optimized SVM-AR model and discusses the application scope of the SVM model and the time series AR model, respectively. The SVM-AR model is proposed by combining the respective advantages of the two types of models. Firstly, the prediction method of foundation settlement is analyzed and studied, and then the improved ABC algorithm is used to optimize the SVM model. Secondly, the optimized SVM model is combined with the AR model, the ABC-SVM model is used to predict the trend settlement, and the AR model is used to predict the random settlement and then combined to obtain the predicted settlement. The example verification shows that SVM-AR is more accurate than the SVM model prediction results and better reflects the settlement process of highway soft soil foundation.

Investigation of Salt-Frost Heaving Rules and Mechanical Properties of Chlorite Saline Soil along the Duku Highway under Freezing-Thawing Action

Aiming to investigate salt-frost heaving rules and the mechanical properties of natural saline soil along the Duku Highway subjected to multiple freezing-thawing cycles, we collected natural saline soil samples from the alluvial-proluvial plain in front of the Dushanzi Mountain at the starting point of the Duku Highway. Then, we conducted mineral composition analysis tests, essential laboratory physical property measurement, large scale multiple freezing-thawing cyclic salt-frost heaving tests, shear strength tests, and unconfined compressive strength tests on the samples. According to the test results presented, the collected saline soil differed from saline soil in other regions and fell into “chlorite saline soils.” As the number of freezing-thawing cycles increased, the overall salt-frost heaving capacity increased and then decreased in the freezing process but first reduced and then increased in the thawing process. Thus, the salt-frost heaving capacity was cumulative in freezing/thawing cycles. The peak salt-frost heaving capacity reached a maximum after 1 freezing-thawing cycle and then dropped drastically and fluctuated regularly. After 6 freezing-thawing cycles, the displacement deformation and time formed a new equilibrium. After 7 freezing-thawing cycles, the displacement and deformation of the soil no longer appear negative. As the number of freezing-thawing cycles increased, the cohesive force of saline soil first increased and then dropped steadily, the internal friction angle first dropped and then increased steadily, and the unconfined shear strength first increased and then decreased. These research results provided data supporting the prevention and controlling highway saline soil disasters with insightful references for the other projects in this region.

ANALYSIS OF LATERITE SOIL WITH PORTLAND CEMENT MIXED VARIATIONS AND THE EFFECT ON THE CBR UNSOAKED

Ketapang and Kayong Utara Regency have road construction that often suffers damage before the planned life age caused by the behavior of expansive clay. The subgrade is a fundamental structure in building road construction because the subgrade will support traffic loads or construction loads. The strength and durability of the pavement structure road will depend on the properties and bearing capacity of the subgrade. Practically soil stabilization is a reinforcement engineering against foundation or subgrade by using mixed materials. Therefore, different soil improvement variations are needed. Based on the test result, the CBR value of Sukadana initially gets a 2.95% point. The CBR value for the 6% and 10 % mixture, respectively, gets 17.14% and 25.02%. The CBR value of Sungai Melayu Rayak originally get 4.65% point. Then, for the 6% and 10% mixture, the CBR values increased by 13.78% and 18%. The value of the bearing capacity of the highway soil construction can be know from the results of CBR testing on each variation. The CBR also can measure the strength of the soil. The addition of cement to the earth tends to increase the bearing capacity of the ground. It is because cement can function as a binder between soil particles with chemical compounds contained in cement.

Calculation of Subgrade Moisture Index in Seasonally Frozen Regions considering Evapotranspiration at Subzero Temperatures and the Pavement Coverage Effect

The moisture index of subgrade material directly below a paved highway is typically represented by that of an uncovered slope. However, existing studies have demonstrated the existence of a significant moisture content difference between an uncovered slope and covered subgrade owing to evapotranspiration. Moreover, under the influence of solar radiation, wind, and other factors, soil evapotranspiration persists even at subzero temperatures. This paper presents an improved method for subgrade moisture index calculation for regions that freeze seasonally. Instead of the conventional Thornthwaite method, the Food and Agriculture Organization Penman–Monteith (FAO‐56 PM) method was employed to estimate the potential evapotranspiration (PE) of slope soil at subzero temperatures. Based on the moisture balance principle, the PE and water runoff and deficit were used as input parameters to calculate the moisture index of an uncovered slope. After the effect of pavement cover on subgrade humidity was defined through a correction coefficient determined via the matric suction dependence of soil water content, an optimized calculation formula was developed to estimate the moisture index of the subgrade material according to that of the corresponding slope. The results calculated on a typical seasonally frozen region in Northeast China demonstrated the applicability and accuracy of the proposed method for predicting the subgrade moisture. The potential evapotranspiration of an uncovered highway slope soil at subzero temperatures could reach 9.8%–15.7% of the total annual evapotranspiration. The moisture index range for seasonally frozen regions was −14.2–57.3. These findings will have important implications for effective improvements in the design and construction of subgrade in regions that freeze seasonally or face similar climatic conditions.

Evaluation of calcined textile sludge as a stabilizing material for highway soil

Abstract The textile industry is a pioneer in the industrialization process in Brazil and is relevant to the Brazilian economy. However, it also generates as operational residue a solid waste, commonly called textile sludge. Pavement construction, which mobilizes large volumes of soil, constitutes an alternative to the reuse of residue, especially when stabilization is involved. The use of stabilized soils with the addition of waste can provide technical, economic and environmentally friendly advantages. This research aimed to study the use of chemical stabilization technique with sludge and three additives (lime, cement and asphalt emulsion) applied in base and subbase of pavements. The scope of this study was divided into four phases, i) characterization tests, ii) physical stabilization, iii) chemical stabilization and determination of heavy metals in the sludge, and iv) addition of 10% of textile sludge and chemical stabilizers (lime, cement, and asphalt emulsion) in amounts of 3%, 5% and 7% as additives in a soil, based on the results obtained in the second phase. Test results indicated that the stabilization of mixtures of soil with textile sludge has the potential to be used in pavement layers (base and subbase). The addition of cement promotes the best chemical stabilization for the sludge. The use of textile sludge stabilization presents greater environmental benefits, given the malfunctions and problems that the incorrect waste disposal can cause to the environment.

Soil and Water Conservation Measures in mountain highway

More and more attention should be paid to the soil erosion in the process of highway construction in mountainous areas. According to the characteristics of highway construction in mountainous areas, the methods of combining permanent measures with temporary measures and combining engineering measures with plant measures are adopted to realize soil and water conservation. In the project construction, the establishment of a sound soil and Water Conservation Prevention and control system has achieved good results in the prevention and control of soil erosion.

Predicting CBR Values of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture Using Regression Model

In highway constructions, sub-grade and sub-base soil stabilization has been used as one of the prime and major process for many years in order to improve the engineering properties of soil. The strength of theses layers is indicated by their California bearing ratio (CBR) value which is quite expensive and time consuming. In order to overcome this situation, this study presents a methodology for predicting soaked California Bearing Ration (CBR) value of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture using Multiple Regression Analysis (MRA). Experimental test results such Atterberg limit (Liquid limit (LL), Plastic limit (PL) and Plasticity index (PI)), Compaction characteristics of two compactive efforts namely standard proctor (SP) and modified proctor (MP) (maximum dry density (MDD) and optimum moisture content (OMC)), CBR, Waste glass (WG) content and Cement content (Cm), obtained from a laboratory at Abubakar Tafawa Balewa University Bauchi, Nigeria, have been employed in developing multiple regression models. California Bearing Ration was taken as the dependent variables while Liquid limit, Plastic limit, maximum dry density, optimum moisture content, waste glass content and Cement content were taken as independent variables. The regression analysis calculated the error mean square (MSE) for each possible model, and models with large MSE were not selected for the best regression equations. The best models have a minimum value of MSE occurring for the six-variable model (Cm, WG, LL, PL, OMCsp, MDDsp) and (Cm, WG, PL, LL, OMCmp, MDDmp) with a corresponding higher value of coefficient of multiple determination R2 = 0.98 and 0.94. The performance evaluation of the fitted regression models indicates a strong correlation (R2 = 0.89 - 0.98) between the mentioned variables, and the model equations developed from this work provided a very good prediction of the response, as the equations can be employed for making estimates of soaked CBR of other black cotton soils having similar geotechnical properties.

Utilization of a vinyl based copolymer for improvement of a kaolin type clay

Geopolymers are obtained by use of alteration of chemical composition and crystal structures of different minerals. Use of geopolymer is an effective and environmental friendly solution in stabilization of clayey soil. The vinyl based copolymer is used as an agent as dust controller, highway soil stabilizer, asphalt admixture, concrete production, etc. In this study, strength of a clay is improved by use of a commercial geopolymer. In this regard, soil was amended with polymer ranging among 0 % to 4 %, by volume of dry soil. Unconfined compression and oedometer tests were carried out to evaluate the effects of temperature, initial water content, compaction energy on strength and compression properties of a clay soil - within an experimental framework. The results revealed that, temperature has a considerable effect on geopolymerization. Besides, under constant moisture content during curing, increasing geopolymer content and curing period causes a slight increase in strength of specimens.

Geo-environmental study of heavy metals of the agricultural highway soils, NW Jordan

This study investigated the status and distribution patterns of selected heavy metals in roadside soils along Irbid-North Shooneh Highway, Jordan. This highway has experienced a growing number of vehicles that are likely to influence the levels of heavy metals in the surrounding agricultural lands. The average concentrations of Cr, Co, Cd, Cu, Pb, Zn, and Ni were 16.0, 36.0, 11.0, 4.0, 79.0, 122.0, and 60.0 mg/kg, respectively. Cd, Pb, and Co showed average levels that are higher than the average world soil background values. Elevated levels of heavy metals were measured in surface soil layer which decreased with depth, and with distance from the roadway. The contamination factor (CF), pollution load index (PLI), single ecological risk (Ei), potential ecological risk index (PERI), and geo-accumulation index (Igeo) generally indicated that the roadside soils are contaminated with Cd, Pb, and Ni. Heavy metals in soils are of geogenic and anthropogenic origins. Weathering of parent rocks in Wadi Al-Arab catchment is the primary natural source, whereas agrochemicals, vehicle exhausts, degradation of surface wear and paint of vehicles, vehicle wear debris of tire, and brake lining are the main anthropogenic sources of heavy metals.

Properties of Biochar-Amended Highway Soils: Biochar – An Eco-friendly Geomaterial

Historically, geotechnical engineers have designed or modified soils and sediments to achieve particular strength, volume change, or flow characteristics. For example, lime and fly ash have been us...

Evaluation of frost heave and moisture/chemical migration mechanisms in highway subsoil using a laboratory simulation method

Seasonal processes in cold countries significantly affect the engineering characteristics of highway subsoil over time. Cyclical freeze-thaw leads to changes in thermal and moisture conditions. As a result, road bearing capacity can progressively change from the initial design. In this work, a modified laboratory method was developed, with cyclical freeze-thaw of soil samples and simultaneous supply of deionised water and a de-icing agent (sodium chloride) to the base. The benefits of the test procedure included slow freezing, simulating the conditions that can be experienced by highway soils in cold environments, extended soil column heights and a larger number of identical soil samples, which allowed experimental variability to be assessed. The method included the monitoring of moisture and chemical mass transfer in the soils. Samples supplied with deionised water experienced ice segregation in their upper parts, and significant heave. While soils supplied with NaCl solution behaved in a similar fashion during their first freeze-thaw cycle, the second cycle saw a reduction in the rate of migration of the freezing front within the soils and also less ice segregation and less heave due to increased salinity. Salt was preferentially transferred upwards in the soil columns as a result of the thermal gradient, including negative pressure associated with cryosuction, and osmotic pressure. The new method provides a more realistic laboratory approach to assessing potential freeze-thaw impacts, and the effects of de-icing agents on soils beneath roads, and in different settings.

Failure of circular tunnel in saturated soil subjected to internal blast loading

Explosions inside transportation tunnels might result in failure of tunnel structures. This study investigated the failure mechanisms of circular cast-iron tunnels in saturated soil subjected to medium internal blast loading. This issue is crucial to tunnel safety as many transportation tunnels run through saturated soils. At the same time blast loading on saturated soils may induce residual excess pore pressure, which may result in soil liquefaction. A series of numerical simulations were carried out using Finite Element program LS-DYNA. The effect of soil liquefaction was simulated by the Federal Highway soil model. It was found that the failure modes of tunnel lining were differed with different levels of blast loading. The damage and failure of the tunnel lining was progressive in nature and they occurred mainly during lining vibration when the main event of blast loading was over. Soil liquefaction may lead to more severe failure of tunnel lining. Soil deformation and soil liquefaction were determined by the coupling effects of lining damage, lining vibration, and blast loading. The damage of tunnel lining was a result of internal blast loading as well as dynamic interaction between tunnel lining and saturated soil, and stress concentration induced by a ventilation shaft connected to the tunnel might result in more severe lining damage.

Field test and numerical modeling of vehicle impact on a boulder with impact-induced fractures

Landscape Vehicle Anti-Ram systems, typically comprising natural materials such as boulders, are effective in protecting sensitive structures against threats. However, fracturing of these materials under vehicular impact can be detrimental to the performance of Landscape Vehicle Anti-Ram systems. This study presents a field-scale crash test and LS-DYNA modeling of a Landscape Vehicle Anti-Ram system subjected to vehicular impact. The Landscape Vehicle Anti-Ram system consisted of three boulders connected through a reinforced concrete foundation embedded in compacted American Association of State Highway and Transportation Officials soil. The central boulder fractured upon vehicular impact. An advanced material model was adopted to model the rock fracture and crushing. The global response of the truck, including cab deformation and dynamic penetration, from the simulation showed good agreement with the field observations. The failure patterns of the boulder, including the fracture plane and minor crushing, also agreed well with the field observations. Through a parametric study, the dynamic penetration of the truck is found to be influenced by the elastic modulus and fracture energy of the boulder, and the Landscape Vehicle Anti-Ram system is more effective with a stiffer and tougher boulder.

Influence of Soil Physical Properties on Rainfall Induced Landslide Susceptible Areas along Cagayan de Oro-Bukidnon-Davao City Route Corridor, Philippines

The Cagayan de Oro (CDO)-Bukidnon-Davao City route corridor plays a vital role in the movement of commerce and trade in the region by linking the two major economic centers of Mindanao, the CDO and Davao Cities. However, this national highway traverses the mountainous ranges of Bukidnon which is prone to rainfall-induced landslides. This study aims to characterize the grain size distribution (GSD), soil consistency (Atterberg Limits) and the influence of moisture content on the yield stress of rainfall-induced landslide prone areas along the route corridor. Majority of the landslide prone areas are dominated by high clay content characterized by high plasticity and high potential to swell (PI > 23 and LL > 50). The yield stress of slip prone clayey soil areas along the CDO-Bukidnon-Davao city highway soil decreased either linearly or exponentially with increasing moisture content. All samples showed critical moisture content which ranged from 60 to 80 % in which a sudden drop of the yield stress was observed. Hence, this study could provide necessary information for various government agencies to come up with pro-active implementation of landslide risk mitigation and management so that cost, hassles and exposure to such risks may be reduced. Â Keywords: Atterberg Limits, clayey soil, Grain Size Distribution (GSD), Yield Stress, Soil Moisture

Development of a GIS-based failure investigation system for highway soil slopes

A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation (P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

Field Study of Improvement Mechanism of Geogrid-Reinforced and Pile-Supported Embankment

Two experimental areas in a highway soft soil ground treatment project in Guangdong Province were designed to investigate the improvement mechanism of geogrid-reinforced and pile-supported embankment(GRPS).The experimental results showed: In End-bearing Pile Area,the differential settlement between pile and soil was bigger than that of Floating Pile Area,so the bearing capacity of soil was exerted to a certain extent in Floating Pile Area. The bearing efficacy of soil below the pile cap was little, so the replacement ratio of composite foundation could be calculated according to the pile cap dimension. The load transfer efficacy of the geogrid was better than that of the soil arch. Five kinds of methods were used to evaluate the soil arch in the fill and it was indicated that the results calculated by the BS8006 method and Carlsson method was close to the experimental data which was smaller than results calculated by Hewlett method and Terzaghi method, bigger than Guido method. Through the analysis of the pile-soil stress ratio, the improvement mechanism of the two types of GRPS were revealed.