SPT-N Value Research Articles

Geophysical Surveys for Geotechnical Model Reconstruction and Slope Stability Modelling

Performing a reliable stability analysis of a landslide slope requires a good understanding of the internal geometries and an accurate characterisation of the geotechnical parameters of the identified strata. Geotechnical models are commonly based on geomorphological data combined with direct and intrusive geotechnical investigations. However, the existence of numerous empirical correlations between seismic parameters (e.g., S-wave velocity) and geotechnical parameters in the literature has made it possible to investigate areas that are difficult to reach with direct instrumentation. These correlations are often overlooked even though they enable a reduction in investigation costs and time. By means of geophysical tests, it is in fact possible to estimate the N-SPT value and derive the friction angle from results obtained from environmental seismic noise measurements. Despite the empirical character and a certain level of uncertainty derived from the estimation of geotechnical parameters, these are particularly useful in the preliminary stages of an emergency, when straight data are not available and on all those soils where other direct in situ tests are not reliable. These correlations were successfully applied to the Theilly landslide (Western Alps, Italy), where the geotechnical model was obtained by integrating the results of a multi-parameter geophysical survey (H/V seismic noise and ground-penetrating radar) with stratigraphic and geomorphological observations, digital terrain model and field survey data. The analysis of the triggering conditions of the landslide was conducted by means of hydrological–geotechnical modelling, evaluating the behaviour of the slope under different rainfall scenarios and considering (or not) the stabilisation interventions present on the slope. The results of the filtration analyses for all events showed a top-down saturation mechanism, which led to the formation of a saturated face with a maximum thickness of 5 m. Stability analyses conducted for the same events showed the development of a shallow landslide in the first few metres of saturated soil. The modelling results are compatible with the actual evolution of the phenomenon and allow us to understand the triggering mechanism, providing models to support future interventions.

Contribution to the seismic microzonation of Lisbon based on the integration of geological, geophysical, and geotechnical data

Lisbon has been affected by several moderate to strong earthquakes that caused considerable damage and produced significant economic and social impacts (e.g., the November 1st, 1755, earthquake). Studies on the potential damage due to a seismic event have been done considering Lisbon's moderate to high seismic hazard, but the seismic site effects have not yet been investigated at the city scale. The local ground conditions can locally modify the characteristics of surface seismic motion.Based on a multidisciplinary dataset composed of surface geology, a geotechnical database, and a geophysical database that compiles all the available geophysical tests carried out in Lisbon, an integrated approach to seismic ground characterisation was performed.A regression analysis of the shear-wave velocity values compiled in the geophysical database was done for each geological unit. The peak frequency distribution in the city, assessed from the ambient vibration measurements, showed a pattern in peak frequency variation. It decreases from the oldest to the most recent geological formations that outcrop in the SW-NE direction. Three zones based on peak frequency value distribution were proposed.An estimation of the impedance contrast depths was computed through two processes, considering the previous results: (i) the shallower contrast depth was assessed through a sharp variation of NSPT values available in the geotechnical database, and (ii) the deeper contrast depth was estimated based on geology data and deep borehole information. The results showed that for the upper ∼100 m of depth, a consistent relationship between the contrasts identified through different data was obtained, even if uncertainty increased with depth.

Spatial Autocorrelation Incorporated Machine Learning Model for Geotechnical Subsurface Modeling

Machine learning models for spatial prediction have been applied in various types of research. However, spatial relation has not been fully considered in modeling, since the Cartesian coordinates of the observed points are directly employed as the location information for machine learning features. This study presents a machine learning modeling process which incorporates spatial autocorrelation for geotechnical subsurface modeling. A new set of features called the Euclidean distance field (EDF) was generated based on the distance between the query points and the observed boreholes in order to incorporate spatial autocorrelation into the machine learning model. Principal component analysis (PCA) was performed to reduce the increasing dimensionality of the dataset caused by the EDF features. Optimized machine learning models based on several popular algorithms (Support Vector Machine, Gaussian Process Regression, Artificial Neural Network, and k-Nearest Neighbor) were employed for predicting several geotechnical information as the targets. The results showed that the optimized machine learning models constructed with the EDF modeling approach generate a slightly lower Root Mean Square Error (RMSE) score compared to the model with the direct XY coordinate approach by 0.041, 0.046, 1.302, and 1.561 for ground surface elevation, groundwater level, SPT-N value, and percent finer than 0.075 mm sieve, respectively. Both modeling approaches performed well for USCS-based soil classification with the EDF model having slightly improved classification accuracy by 0.72%. Furthermore, the model can perform balance multiclass classification as indicated by the >95% precision, recall, f1-score, and balanced accuracy score. These results indicate that spatial autocorrelation has a noticeable effect. Hence, it needs to be considered to improve the overall performance of spatial machine learning modeling. Comparison of geotechnical subsurface predictions generated based on different machine learning algorithms showed that the selection of the best-performing model based only on the lowest prediction error is not appropriate for spatial prediction modeling. Therefore, thorough analysis of the predicted data by visualization is necessary in the selection process for spatial prediction modeling.

Correlation of Cohesion and Friction Angle Based on SPT-N Values: A Comprehensive Review

Soil parameters such as physical, chemical, and strength parameters play an important issue to classify the soil. Cohesion and friction angle are an important factor to understand the nature of the soil. Furthermore, standard Penetration Test (SPT) is one of the most common tests in the field and used to determine the strength of soil in the field prior laboratory tests. The variation in the properties of the soil in different regions, give differ values when using the standard methods, formulas, and correlations. In this paper, an overview of the methods and guidelines currently available in the scientific literature for evaluating the strength capacity of the soil, is reported. Further, important practical issues which contribute in the soil strength in different regions based on cohesion and friction angle used SPT are discussed. Moreover, the correlation results from the standard penetration test compared with those from cohesion and friction angle based on samples number and regions. Finally, the paper mentions the famous correlation in this domain and others from the standard code at USA, Jordan, Japan and UK. The compared results using guides from these standards showed big different, which let us to recommend that, these standards are not suitable for soil strength calculations due to different in the soil parameters from region to other.

Analisis Penurunan Tanah Timbunan Menggunakan Metode Elemen Hingga pada Ruas Jalan Tolango-Bulontio STA 47+600

Subsidence is a change in the composition of the soil and small spaces in the soil. The method that can be chosen to reduce the rate of decline that occurs on the road is preloading and adding geotextiles. The purpose of this study was to analyze the settlement that occurred in the embankment soil before and after the geotextile was applied. The research location is on Jalan Tolango-Bulontio STA. 47+600 Wubudu Village, East Sumalata District, North Gorontalo Regency. The primary data used is the characteristics of the embankment soil, while the secondary data is in the form of plan drawings, N-SPT values, and geotextile characteristics. Land subsidence analysis was carried out by modeling in two dimensions using the finite element method with the help of the Plaxis 2d v20 application. Structural modeling using plane strain model. The results showed that the settlement of the embankment using geotextiles that the settlement of the embankment soil at point A (shoulder) was 33 mm <65 mm, while the settlement of the embankment without geotextile was greatest at point A (shoulder) of 33 mm. mm < 65 m (allowable descent). The settlement value of the embankment without geotextiles and the use of geotextiles did not have a significant difference because the geotextiles used only functioned as filtration, not as reinforcement

Analyzing Geotechnical Characteristics of Soils in Erbil via GIS and ANNs

The aim of this study is to analyze and model the geotechnical characteristics of soils in Erbil city using Geographic Information Systems (GIS) and Artificial Neural Networks (ANNs). The study used GIS to analyze the geotechnical properties of soils by collecting data from 102 boreholes in three different depth levels (1.5 m–3.5 m, 3.5 m–6.5 m and 6.5 m–9.5 m) to visualize and analyze soil characteristics such as fines content, moisture content, soil plasticity, shear strength parameters, compressibility, Standard penetration test (SPT), and bearing capacity. The paper also establishes the prediction of SPT-N value and bearing capacity based on geotechnical properties of soils using ANN methods and made correlations between SPT values and shear strength parameters with the bearing capacity of the soil. The results analyzed via GIS indicated that the soil classification was silty clay with a small amount of sandy gravel (CL) in most of the study area. According to the SPT–N values, most of the soils in Erbil City ranged between 33 and 50; a higher SPT value generally indicates denser and stronger soil. The value of the shear strength parameter for the maximum friction angle of the soil layers was found to be 36°, and the predominant cohesion was approximately 100 kPa. The compression index of soils ranged between 0.11 to 0.31. The results showed that the ANN models were able to accurately predict the geotechnical parameters of the soil types in the study area. In addition, the use of GIS and ANN techniques allowed for a comprehensive analysis of the geotechnical characteristics of the soils in Erbil, providing valuable information for future construction and development projects.

Hybrid Random Forest-Based Models for Earth Pressure Balance Tunneling-Induced Ground Settlement Prediction

Construction-induced ground settlement is a serious hazard in underground tunnel construction. Accurate ground settlement prediction has great significance in ensuring the surface building’s stability and human safety. To that end, 148 sets of data were collected from the Singapore Circle Line rail traffic project containing seven defining parameters to create a database for predicting ground settlement. These parameters are the tunnel depth (H), the tunnel advance rate (AR), the EPB earth pressure (EP), the mean SPTN value from the soil crown to the surface (Sm), the mean water content of the soil layer (MC), the mean modulus of elasticity of the soil layer (E), and the grout pressure used for injecting grout into the tail void (GP). Three hybrid models consisting of random forest (RF) and three types of meta-heuristics, Ant Lion Optimizier (ALO), Multi-Verse Optimizer (MVO), and Grasshopper Optimization Algorithm (GOA), were developed to predict ground settlement. Furthermore, the mean absolute error (MAE), the mean absolute percentage error (MAPE), the coefficient of determination (R2) and the root mean square error (RMSE) were used to assess predictive performance of the constructed models for predicting ground settlement. The evaluation results demonstrated that the GOA-RF with a population size of 10 has achieved the most outstanding predictive capability with the indices of MAE (Training set: 2.8224; Test set: 2.3507), MAPE (Training set: 40.5629; Test set: 38.5637), R2 (Training set: 0.9487; Test set: 0.9282), and RMSE (Training set: 4.93; Test set: 3.1576). Finally, the sensitivity analysis results indicated that MC, AR, Sm, and GP have a significant impact on ground settlement prediction based on the GOA-RF model.

A new approach to the correlation of SPT-CPT depending on the soil behavior type index

In this study, a model based on soil behavior type index (Ic) has been proposed for the conversion of field cone penetration test (CPT) data to the standard penetration test (SPT) blow counts (N). The field data used in the study were obtained from the fluvial soils formed by the Sakarya river in Adapazarı (Turkey). According to the proposed model, it is understood that there are exponential relationships between SPT-N and CPT data with varying coefficients (constant multipliers and exponents) for different Ic intervals. While the coefficients of the equations were kept constant in the previous formulations developed based on Ic, the current study revealed that the mentioned coefficients should be changed for different Ic intervals. The normalized cone resistance (qt/ Pa) or corrected SPT-N values (N60), found with the model created with the final coefficients, were evaluated. The results obtained by using the new model proposed in this paper were compared with other models generally accepted in the literature. It has been revealed that the results achieved by this new model are the closest ones to the measured values compared to the other methods. To verify the proposed model, CPT-SPT data pairs that were not used in the model generation were analyzed. Verification analyses confirmed that the developed method has given more realistic results than the other methods suggested in the literature. It was understood that the error rate in the model, in which conversion between CPT and SPT data can be made by considering the variability in the soil behavior type index, is lower than the others. As a result, the paper gives a new perspective by introducing a simple and newly updated form of estimating N60 values.

Probability based Assessment of Soil Liquefaction Potential in Vijayawada Region (CRDA)

Risks of liquefaction are commonly related to saturated cohesionless soils that have low plasticity and density. As liquefaction causes severe destruction to structures and risk of losing lifeline it is important to study the liquefaction potential for CRDA region because for the development of AP capital heavy structures are being constructed and a population increase is being expected in this region. In the current investigation, soil resistance to liquefaction was analyzed in each bore log in consideration of significant soil characteristics such as grain size, fines content, unit weight, saturation percentage, SPT N-value, and soil origin. The safety factor for liquefaction is evaluated using data from several bore holes that were collected and used for this purpose. The approach recommended by Seed and Idriss was utilized to assess the safety factor for liquefaction. The obtained results from the semi-empirical calculations are further compared to the results obtained from Software for more reliability.

Seismic Site Response Analysis of MMMUT Gorakhpur of Uttar Pradesh, India

An endeavour has been made to assess the spatial fluctuation of the profundity of endured and designing bedrock in Gorakhpur Uttar Pradesh, North India utilizing Multichannel Analysis of Surface Wave (MASW) study. One-layered MASW study has been done at Madan Mohan Malaviya University of Technology, Gorakhpur campus and Shear-wave Velocity V S 30 are estimated. MASW overview at 3 location and a Standard Penetration Test SPT-N from the profound geotechnical boreholes data used for comparison of site classification. The deduction of this work might be utilized as contributions for seismic tremor risk the board by lessening the seriousness of earthquake shaking through plan of tremor Earthquake risk resilient structure strong designs. The data that collected from the MASW experimental setup is feed using the software ParkSEIS (v.3.0), we obtain Shear Wave Velocity (VS30 ). The obtained V S 30 is used to plot Response Spectra for MMMUT Gorakhpur. The Time History data used in this thesis is Nepal Earthquake 2015 data which is collected from Indian Metrological Department (IMD) Delhi, India. SPT-N value data is collected from Awas Vikas Parishad for the New Administration Building build at MMMUT campus Gorakhpur. The Time History data of Nepal Earthquake 2015 is analysed using DEEPSOIL v7 Software and a systematic layer wise study of MMMUT Campus soil is carried out, results such as Ground Motion Parameters, Response Spectra, Spectral acceleration vs Frequency plot, Tripartite Spectrum and Response spectra corresponding to 5% damping are obtained.

Multichannel Analysis of Surface Waves (MASW) to Estimate the Shear Wave Velocity for Engineering Characterization of Soils at Hawassa Town, Southern Ethiopia

Site characterization is a prerequisite for the successful and economic design of engineering structures and earthworks by providing geological information for any proposed project. Until now, no detail study has been carried out on the site characterization and classification using shear wave velocity (Vs) up to the top 30 m depth in Hawassa town. For this study, multichannel analysis of surface waves (MASW) was used to determine the variation of Vs for a proper civil engineering design in the town. In addition, vertical electrical sounding (VES) and standard penetration test (SPT) were employed to characterize the near-surface materials. The Vs30 map was prepared for Hawassa town using the estimated Vs30 values which ranges from 248.9 m/s to 371.3 m/s while the SPT-N values were ranges from 5bpf to 50bpf. The correlation of Vs and SPT-N values has been done by considering both corrected and uncorrected SPT-N values. The VES result showed that groundwater is found at a shallow depth. The correlation of Vs and SPT-N value was validated using regression model. The 1D Vs profile and 2D cross-section showed low Vs at a shallow depth. The near-surface soils of the town are classified based on the Vs30 as site class C (stiff soil and soft rock) and D class (stiff soils) according to the NEHRP (Natural Earthquake hazards Reduction Program) and as subsoil classes B and C according to the Eurocode 8. The geotechnical tests also showed that the soils in the study area are silty sand, sand and silty sand with some gravel. The low Vs values observed at a shallow depth should be given much attention during foundation design for the stability of civil engineering structures.

Fasies Sedimen Kuarter Kaitannya Dengan Potensi Likuefaksi Di Kawasan Das Cimanuk, Indramayu, Jawa Barat

The lower Cimanuk catchment area which will be developed as industrial area is dominated by Quaternary deposits which are susceptible againts liquefaction if large earthquakes occurred. The presence of Subang, Cirebon 1 and Cirebon 2 active fault segments will trigger earthquake which potentially liquefaction. This study aims to characterize the type of sedimentary facies induced liquefaction hazard in the lower Cimanuk catchment area, Indramayu, West Java. This research methods consist of borehole description and sedimentary facies analysis based on CPT and CPTu data with cone resistance (qt) corrected value, friction ratio (Fr), laboratory analysis and liquefaction potential based on SNI 1726:2019, which is deterministic and 2,500 years return period PGA value. Based on facies association analysis there are three facies that developed in the study area. First, delta plain facies consisting of fluvial sands, silt and clay. Second, delta front facies consisting of beach ridge sands and sandy silt. Third, silt and clay prodelta facies. Liquefaction potential analysis based on N-SPT, CPT and CPTu data shows that almost all test point are potentially liquefied, especially beach ridge sands and silty sand delta front facies. Liquefaction potential is more in the northern region of the study area, caused by the low density of sand and sandy sediments (N-SPT value < 10 or qc < 6,000 kPa).

Soil Liquefaction Potential in Different Seismic Zones of Bihar, India

Liquefaction potential analysis for the liquefiable as well as non-liquefiable soils of Bihar state has been performed in this paper based on the actual field data from three seismic zones, i.e. zone III, zone IV, and zone V. The analysis has been performed following the simplified procedure given in [1] and later modified in [2]. The results show that districts under seismic zone III are comparatively more resistant to liquefaction in most cases, districts of zone IV are relatively more prone to liquefaction up to a few depths, and districts of zone V are most liquefiable. Liquefaction resistance is primarily depending upon the fine content of soil and SPT N-values.

Comparative analysis of Geotechnical and Geophysical Investigations for average shear wave velocity in Metro Manila

Philippines is one of the most seismically active countries in Southeast Asia and records at least 20 earthquakes per day according to the PHIVOLCS. Vs30 is defined as the shear wave velocity of the upper 30-meter subsurface profile which is an important seismic parameter to determine the dynamic behavior of soils or rocks. This research aims to determine the Vs30 of three sites in Metro Manila using two methods Geotechnical Investigation(GI) and Geophysical Investigation(GPI) by Multichannel Analysis of Surface Waves (MASW) method and compare their results. The data used for GI are SPT N-values for soils and Rock Quality Designation. Conversely, a seismic survey using the MASW method was conducted along the three sites and Vs30 was determined based on the processed seismic data from Geogiga software. The results of the methods were compared in terms of the ratio between the Vs30 difference from geotechnical investigation and geophysical investigation with the calculated range based on the NEHRP classification table. The calculated ratios showed 43.68% for MNHS, 6.44% for BES, while 48.16% for VFMHS. Comparison of methods showed that ratio between Vs30-difference from GI and GPI with the calculated range based on the NEHRP was found to be acceptable (≤1.0) for all sites. Moreover, the seismic soil classification based on the NEHRP was found to be consistent for both methods.

Soil Characteristics of Padma Multipurpose Bridge

Padma Multipurpose Bridge is situated on a section of the Padma river where the soil condition is highly heterogeneous and intermixed with different soil layers, for which pile design was the critical part. This paper describes the soil properties and ground profiling of the Padma Multipurpose Bridge. Different types of field and laboratory tests were carried out to obtain accurate soil parameters and ground profiles along the whole alignment of the bridge. Standard Penetration Tests, Cone Penetration Tests, and grain size analyses were conducted for the soil classifications and ground profiling. Flat Plate Dilatometer Tests, High Pressure Dilatometer Tests, and Self-Boring Internal Friction Tests were performed to obtain the stiffness of the different soil layers and shear strength parameters in field conditions. Cross-hole and Seismic Tomography Geophysical tests were executed to obtain seismic waves and dynamic shear modulus of each soil layer. Gel Push Soil Sampling technique was used to collect undisturbed samples of sandy soils to get accurate stress–strength-dilatancy characteristics of sandy soils through different laboratory tests. The soil was classified into three Units and some sub-units based on grain size and SPT-N value. Soil parameters were finalized based on both laboratory and field test results. The pile design was possible for accurate measurement of soil parameters and ground profiling along the alignment of the bridge.

Liquefaction Potential Analysis and Mitigation at The Sediment Control Structures on Bangga River, Central Sulawesi

The Palu Earthquake in 2018 has triggered a debris flow incident in Bangga River. As a form of protection for similar disasters, it is planned to construct Sediment Control Structures in the Bangga River. The Bangga River area also has liquefaction potential that needs to be considered to ensure the structure’s stability. This study aims to perform liquefaction analysis at the Sediment Control Structure area. Liquefaction potential is calculated using the Simplified Method and Liquefaction Potential Index Method based on 15 bore-log data that includes SPT. Further analysis is conducted by calculating lateral spreading and settlement potential. Liquefaction potential is found in the Consolidation Dam area, leading to lateral spreading and settlement at the footing of the structure. The lateral spreading potential is found from a depth of 11 to 13 m, with the potential movement of 0.886 m and located only 1 m below the Consolidation Dam foundation. Mitigation planning is proposed by compaction method to increase the liquefaction resistance. The safety against liquefaction is achieved by increasing NSPT value of the vulnerable soil to be greater than 36. This increasing soil strength can reduce lateral spreading potential up to 95% and the settlement potential up to 89%.

New Approach for Developing Correlation of NSPT and Shear-Wave Velocity (Vs): Bantul Case Study

DOI:10.17014/ijog.9.3.395-413Predictions of ground motion levels that, under certain conditions, may cause liquefaction require a sufficient knowledge of the underlying soil characteristics. The utilization of the seismic refraction method applies measurements of the subsurface shear-wave velocities (Vs) as a representation of the properties of stiffness and soil amplification. This study, carried out in Bantul, Yogyakarta Province, Indonesia, is conducted to determine the relationship between Standard Penetration Test N values (NSPT) and Vs by using data from eighty-eight drill sites and twenty-nine seismic reflection investigations with the statistical method, namely the Statistical Gradation Approach. The new equations, developed from a power regression analysis, are applied to all soil and eight soil types: silty sand, sand, gravelly sand, clay, silt, sandy clay, clay sand, and sandy silt. The equations, proposed to predict Vs, show a strong relationship between NSPT and Vs values, which applied to other regions with the shear-wave velocity of <300 m/sec, shallow groundwater depth, and dominant sandy soil.

Pile length optimization by using shaft friction and end bearing curves developed from instrumented pile load test

Most high-rise buildings or bridges are supported by drilled cast in-situ piles. Construction project often start with pile capacity design, followed by installation of instrumented ultimate test piles to determine pile-soil response under load. A piled foundation is typically designed with consideration of capacity and various safety factors based on the assumption that the pile will not settle beyond the allowable limit. However, many practitioners have neglected the importance of pile settlement analysis and omitted the instrumented ultimate test pile in construction programs. Lack of knowledge on pile-soil response could lead to overdesign or underdesign of the piled foundation system. To address the research gap, this paper describes the current practice where the pile capacity and optimization analysis is carried out based on SPT-N value correlated to the ultimate load test result. The optimized pile length is then analyzed using another pile optimization approach (T-z method) that applies the nonlinear pile load response curves for shaft friction (t-z curve) and end bearing (q-z curve) derived from the actual test result. Comparative results show that the computed pile head settlement is in good agreement with the measured pile load test result with approximately 86% accuracy. Further optimization can be performed on the working piles by using the T-z method. Additionally, the construction-induced variability, particularly the pile base response in optimization, is also examined. The optimization has economic and environmental benefits as fewer construction materials are needed to ensure the safe performance of the piled foundation.

Ground response analysis and liquefaction for Kalyani region, Kolkata.

The main focus of this research is the ground response analysis and liquefaction potential analysis of AIIMS Kolkata based on SPT-N values at six different locations. The analyses are performed for the earthquake magnitude Mw = 7.0 and peak ground acceleration of 0.170g. For this, Equivalent-linear Earthquake Response Analysis (EERA), Nonlinear Earthquake Response Analysis (NERA), and PLAXIS-2D software are utilized. In ground response analysis, various parameters such as shear stress, peak ground acceleration, relative displacement, and amplification ratio are evaluated. In liquefaction potential analysis, the factor of safety against liquefaction is calculated from different methods, such as the simplified method, EERA, and NERA, and their results have been compared. Further liquefaction potential index is also evaluated for the same earthquake magnitude and PGA using the factor of safety value evaluated from liquefaction potential analysis and ground response analysis for all the borehole locations. It is observed from the results that the equivalent linear analysis gives conservative results when compared with those obtained from the nonlinear analysis. Moreover, the simplified method too fails to predict the liquefaction susceptibility of certain regions that are found to be prone to liquefaction from the EERA and NERA analyses.

Soil Investigation Analysis Obstackle Cutting Planning Hill Direction Rh 04 Tana Toraja District

The excavation activity of cutting the obstackle area is one of the technical activities to support the requirements of aviation safety due to the hard rock type conditions. In this research, which was conducted at Kunik Airport, Tana Toraja Regency, core drilling was carried out to determine the type of soil/rock excavation and to describe the engineering properties of the soil/rock layers. The results of the field implementation show that the depth of hard soil with an indication of the NSPT value > 60 is at a depth of 2m. while the total rating for the excavation method and the type of equipment used are a) Easy ripping which consists of clay soil type of equipment used in the form of a D7 type tractor with an alternative to using a standard bachoe excavator, b) Hard ripping consists of on brown and greenish-grey clay, the equipment used is a tractor type D7-D8 with an alternative to using an excavator breaker and c) Very hard ripping required Claystone is blackish brown in color. The equipment used is a tractor type D8-D9 with alternative can use excavator breaker